LMT Enhanced bolt [Archive] - M4Carbine.net Forums

C4IGrant

09-02-06, 12:09

According to LMT, the Enhanced bolt has Re-enforced lugs and a dual extractor spring system. The Enhanced carrier has a third gas vent hole to help with pressure. I personally have one one of these for awhile and not had a problem. I have also had several of them returned.

I would say that if you feel that you would benefit from it then get it, but generally speaking, you don't need it.

C4

Aubrey

09-02-06, 14:55

Some have had issues with the LMT enhanced BCGs in 10.5" uppers. They were designed for the 14.5" uppers, not the shorties.

AR15barrels

09-04-06, 00:41

http://www.ar15barrels.com/tech/lmt-enhanced-bg.jpg

QuietShootr

09-04-06, 11:28

http://www.ar15barrels.com/tech/lmt-enhanced-bg.jpg

I know what they look like, I have one. I just don't see what they offer over a MP Colt bolt.

Diz

09-04-06, 21:39

Well, supposedly, they improved a few things. Like beefed up locking lugs, with radiused corners, and relief cuts, all to make them less prone to break, especially around the extractor cut. And speaking of the extractor, what does the double spring arrangement do, besides look dead sexy? Dunno on that one, although from what I've heard the o-ring/d-ring actually accomplishes the same task, only better.
Might be easier to clean.

AR15barrels

09-05-06, 09:02

I know what they look like, I have one.

Sorry, I failed mind reading and did not know you had one. ;)
I posted the picture for the benefit of anyone else who has not seen them.

I am an LMT dealer, but I am not a big supporter of the enhanced bolts.
They are pretty pricey for what they offer.
They have some nice features, the coating, the dual springs, sand cuts, better reliefs etc, but a good quality CMT bolt with an O-ring is just as functional.

I stock LMT Enhanced bolts/carriers because someone occasionally wants one, but I don't push them.

nickdrak

09-05-06, 11:01

I own one that I ordered with my MRP and it has help it run perfectly since day one, thats why I like them. I have heard that LMT has had some issues with some of the enhanced bolts in the past, but not exactly what type of issues. As Randall said, a good CMT or other quality bolt with the proper extractor upgrades will function just as good. Here are some more pictures (courtesy of Military Morons) for the interested:
http://i1.tinypic.com/2wftgs2.jpg
http://i2.tinypic.com/4hd4feo.jpg
http://i6.tinypic.com/4ife7pi.jpg

Heavy Metal

09-09-06, 23:41

Notice the Enhanced Carrier has a different cam track that does not engage the cam pin till later in the reward movement, adding a delay in opening. Unfortunately, none of the above pics capture this feature.

This is to allow residual chamber pressure to drop, ease extraction and reduce stress on the outboard locking lugs.

Ned Christiansen

09-10-06, 08:34

Looks like there have been a few iterations of the relief cuts to individual locking lugs-- I'm sure I've seen them much deeper than that. Although I've seen just a few of these.

The raised ring at the end of the carrier, I presume, is to reduce the area of contact where it bangs off on the barrel extension, allowing more room for dirt.

The best thing about the dual spring extractor is that it lets the springs be made longer. Longer springs are happier springs. Woulda been nice if there was some other spring in the system that coulda been drafted to also serve as extractor springs, like safety detent springs or something (too long, justoffered as an example). I'm sure they looked at that during design, it would have made spring availability less of an issue. Anyway-- there seem to be several theoretical advantages in this setup that aren't translating into it being must-have for ever AR15-ist out there.

boltcatch

04-27-10, 16:06

ThirdWatcher

04-27-10, 16:35

Thanks for the pics, I've never seen one before. It looks to be about as relevant as a forward assist to me, though.

bkb0000

04-27-10, 16:48

they work wonders in some guns. dont get one if you don't actually need one- and if you don't know if you need one or not, you don't need one.

criticism of something you don't understand is gay.

Thomas M-4

04-27-10, 17:15

Yeah, I know, necropost, but search simply hasn't worked for me for a while for whatever reason.

I got an LMT bolt assembly in today.. ordered it because Bravo Company ran out of BCM bolts, literally minutes before I checked out (got notification yesterday they were back in, figures)

I noticed some odd features on the bolt, it apparently has the same radius on the rear of the locking lugs as is shown here on their advanced bolt. I don't know when they started doing this, or if all of them have this.

There is a post around here:rolleyes: with Bill Alexander discussing the enhanced bolt and carrier it was a great post.

I will try to look for it and post you a linky.

BKB pretty much somes it up if you don't know if you need it then you probably don't need it.

Thomas M-4

04-27-10, 17:20

https://www.m4carbine.net/showthread.php?t=3379

Here it is post #12
The best description of the LMT enhanced BCG that I have been able to find.

Artos

04-27-10, 21:48

they work wonders in some guns. dont get one if you don't actually need one- and if you don't know if you need one or not, you don't need one.

criticism of something you don't understand is gay.

just curious, what sort of problems would you see that an enhanced bolt would fix??

I'm running the enhanced carrier but w/ the standard lmt bolt.

Thomas M-4

04-27-10, 22:58

just curious, what sort of problems would you see that an enhanced bolt would fix??

I'm running the enhanced carrier but w/ the standard lmt bolt.

Bolt was designed for a longer service life not to fix a problem to say.

bkb0000

04-28-10, 00:06

just curious, what sort of problems would you see that an enhanced bolt would fix??

I'm running the enhanced carrier but w/ the standard lmt bolt.

the carrier is the part that usually offers the solution to a problem.. by bleeding more port gas, it can turn an over-gassed gun into a correctly gassed gun. 10.5s, 16.1s, suppressed, anything that's overgassed, for whatever reason.

Bolt was designed for a longer service life not to fix a problem to say.

a more durable bolt sort of goes hand in hand with weapons that are over-gassed. plus, as Heavy mentioned above, the bolt further slows unlock- it does contribute to the buffered action of the group.

Artos

04-28-10, 07:28

the carrier is the part that usually offers the solution to a problem.. by bleeding more port gas, it can turn an over-gassed gun into a correctly gassed gun. 10.5s, 16.1s, suppressed, anything that's overgassed, for whatever reason.

a more durable bolt sort of goes hand in hand with weapons that are over-gassed. plus, as Heavy mentioned above, the bolt further slows unlock- it does contribute to the buffered action of the group.

Thanks...I'm running the enhanced carrier but with the standard lmt bolt.

rkrobert86

12-07-12, 11:27

Will the LMT Enhanced bolt fit inside you stock Bolt Carrier Group (BCG) or do you have to buy the LMT enhanced bolt with the LMT BCG?

bobsolla

12-07-12, 11:32

http://www.ar15barrels.com/tech/lmt-enhanced-bg.jpg

thanks for sharing the picture!it really helps to understand the concept!

Eric D.

12-07-12, 12:18

It will fit in a standard carrier.

Will the LMT Enhanced bolt fit inside you stock Bolt Carrier Group (BCG) or do you have to buy the LMT enhanced bolt with the LMT BCG?

Heavy Metal

12-07-12, 14:20

Word is that the bolt is made of Aermet which some say is 2.5 times stronger than Carpenter 158 series steel. (Both are form Carepenter)

Also, two more points:

1.) The springs just last and last. I am well over 10K rounds and the springs are still happy and strong.

2) The carrier kely on mine came loose arond 14K rounds(only realy gripe to date). Upon removal prior to re-tightening it, I discovered somthing unusual, the gas hole into the carrier from the key had a divider in it, it was bifrucated.

og556

12-07-12, 15:04

Have any of you used the enhanced BCG and bolt with a mid length gas system and A5 receiver extension ?

djmorris

12-07-12, 15:11

Have any of you used the enhanced BCG and bolt with a mid length gas system and A5 receiver extension ?

To my understanding you would be better off just using the LMT Enhanced Bolt and skipping the Enhanced Bolt Carrier, for your particular setup. You did not mention which length but if you're running a middy w/ an A5 given that it's not overgassed then you prob would not benefit from the carrier at all.

og556

12-07-12, 16:48

That makes sense.

Just out of curiosity if one were to run a carrier like this with a 16" mid length would it possibly cause issues due to how much gas it bleeds off ?

VIP3R 237

12-07-12, 17:16

2) The carrier kely on mine came loose arond 14K rounds(only realy gripe to date). Upon removal prior to re-tightening it, I discovered somthing unusual, the gas hole into the carrier from the key had a divider in it, it was bifrucated.

By chance did you happen to take a photo?

sinister

12-07-12, 20:53

LMT developed their enhanced bolt and carrier because SOCOM asked for them -- then cancelled. They "Fix" what was identified by the customer as weaknesses. They're actually very effective for extending the life of components in both the 14.5 and 16-inchers, but are not absolutely necessary (especially if you have on-the-ball weapons maintainers).

Of all the LMT improvements I like the re-engineered cam pin slot (delaying unlocking) and the added gas vent ports.

Dessert Fox

12-07-12, 23:38

I'm kind of digging the full contact bolt face. Looks like it removes most (if not all) of the sheer force from the extractor pin.

Heavy Metal

12-08-12, 00:20

By chance did you happen to take a photo?

Didn't think to.

Iraqgunz

12-08-12, 02:11

BufordTJustice

12-08-12, 03:56

Have any of you used the enhanced BCG and bolt with a mid length gas system and A5 receiver extension ?

Kinda. I have used the enhanced carrier, std LMT bolt, A5 system, and a BCM 14.5" middy.

Close enough?

I have a thread in the technical forum. Look in my post history.

Sent from my SPH-D710 using Tapatalk 2

AFshirt

12-08-12, 05:42

... (especially if you have on-the-ball weapons maintainers).

.

That is the rub right there. As soon as I got high enough in rank to NCOIC my own maintenance shop I demanded my guys fully gauge, inspect, and replace both extractor and ejector springs at a minimum any rifle that came in regardless of what it came in for.

Magic_Salad0892

12-08-12, 05:47

I wonder if the enhanced bolt will work on an SBR with a smaller port.

Maybe the shorter dwell time of an SBR doesn't give the extractor enough time to pick up the case. (If it indeed has less extractor tension. Which I can't confirm, as I've never measured it.)

I know the KAC bolt will work on SBRs just fine. And they use a similar extractor. I don't know why LMT's enhanced bolt wouldn't work.

EzGoingKev

12-08-12, 07:27

Have any of you used the enhanced BCG and bolt with a mid length gas system and A5 receiver extension ?

Just out of curiosity if one were to run a carrier like this with a 16" mid length would it possibly cause issues due to how much gas it bleeds off ?
I put about 300 rounds through a 16" mid-length upper using LMT's enhanced bolt carrier, standard bolt, and an A5 receiver extension using:

- 5.3oz buffer/VLTOR spring
- 5.3oz buffer/Sprinco green spring
- 6.1oz buffer/VLTOR spring
- 6.1oz buffer/Sprinco green spring

The barrel is a DD with a .072" gas port. The ammo was Partizan 55g 5.56 m193. I know 300 rounds is not a lot but I had zero problems with the rifle's function.

I wonder if the enhanced bolt will work on an SBR with a smaller port.

IIRC there are a few threads on here in which people have tried running the enhanced bolts in SBR's and have had extraction issues right off the bat.

eperk

12-08-12, 07:36

EzGoingKev

12-08-12, 07:37

Did you try contacting LMT and asking them about purchasing spares?

Magic_Salad0892

12-08-12, 07:37

IIRC there are a few threads on here in which people have tried running the enhanced bolts in SBR's and have had extraction issues right off the bat.

I'm aware of that, I was in one of them.

What I meant was, maybe the smaller port, and enhanced carrier would slow the bolt down enough to work.

eperk

12-08-12, 07:56

Did you try contacting LMT and asking them about purchasing spares?

No just couldn't find them on their online store.

AR15barrels

12-08-12, 17:02

What I meant was, maybe the smaller port, and enhanced carrier would slow the bolt down enough to work.

The smaller gas port already slows the carrier down.
If the gas port is too small, the upper already won't function.
Going to an LMT enhanced carrier would slow the carrier down even more, not allowing enough energy to transfer to the carrier before the bullet leaves the muzzle.
That would just about guarantee non-function.

AR15barrels

12-08-12, 17:05

I have the enhanced bolt in a standard LMT carrier. My only worry is where to get the replacement springs.
Didn't see them in the LMT store.
Anybody have any ideas of a suitable substitute if the originals can't be found?

I have spare springs and extractors for LMT enhanced bolts.
Any LMT dealer can order them along with a larger order but LMT just won't sell them as individual parts unless you order 100 pieces.

EzGoingKev

12-08-12, 17:06

Randall,

At first thought one would think that would be the case but in the ultimate SBR thread it worked the opposite IIRC.

I think it was the revised cam tunnel timing that made it function.

AR15barrels

12-08-12, 17:54

Randall,

At first thought one would think that would be the case but in the ultimate SBR thread it worked the opposite IIRC.

I think it was the revised cam tunnel timing that made it function.

Interesting.
I don't have SBR's due to my lame state laws, but what specific barrel lengths and gas port locations and gas port diameters were we talking about here?
I would assume the most common SBR AR's to be 10.5" carbine gassed setups unless someone states different.

EzGoingKev

12-08-12, 21:42

I cannot find it but there is/was a huge "ultimate SBR" thread in which Grant (IIRC) outlined an SBR build for himself.

As I said, I cannot find it so I am going from memory but it was a 11.5" or 12.5" barrelled SBR that he shoots both suppressed and un-suppressed with the goal of using the smallest gas port.

The rifle functioned with the suppressor but would not cycle the action 100% when the suppressor was removed. A LMT enhanced bolt carrier was installed and fixed the problem.

Heavy Metal

12-08-12, 21:52

I have an enhanced carrier and I am now tempted to remove the key and look at it. Another thing I noticed about the extractor springs (if someone knows the answer please tell) the springs appear to be a standard ejector spring that was essentially cut down. Basically the length of them was about 1/3 the size of an ejector spring in length.

I need to get access to another one to examine it.

I can telly you one thing, they waaaay outlast the standard extractor springs.

I bought a sackful at a buck per spring and have never needed one. The biggest danger would be losing one.

rundm

12-10-12, 10:18

This is what I was told when I asked them why they were so much more expensive then other bolts. I was told it would last several thousands of rounds more than most other bolts.

Word is that the bolt is made of Aermet which some say is 2.5 times stronger than Carpenter 158 series steel. (Both are form Carepenter)

Also, two more points:

1.) The springs just last and last. I am well over 10K rounds and the springs are still happy and strong.

2) The carrier kely on mine came loose arond 14K rounds(only realy gripe to date). Upon removal prior to re-tightening it, I discovered somthing unusual, the gas hole into the carrier from the key had a divider in it, it was bifrucated.

Clem

12-10-12, 10:35

BufordTJustice

12-11-12, 23:37

I know LWRC sells extractor springs with inserts for their bolt, which appears to copy LMT's extractor design.

Sent from my SPH-D710 using Tapatalk 2

Iraqgunz

12-12-12, 01:04

I went to someones abode the other night to look at his bolt. My suspicions appear to be confirmed that the LMT enhanced bolt extractor springs appear to be ejector/selector springs that were cut into a 1/3.

I can telly you one thing, they waaaay outlast the standard extractor springs.

I bought a sackful at a buck per spring and have never needed one. The biggest danger would be losing one.

Cincinnatus

12-12-12, 01:52

Annecdotal, but I have run a 16" mid-length MRP barrel with an H-Buffer with the enhanced bolt and enhanced carrier. It has eaten a wide variety of ammunition from 5.56 to .223 from a variety of makers with no problems. This is a subjective assessment, but it seems to me to shoot much more softly than even a BCM midlength 16" with an H-buffer.

Pappabear

12-12-12, 02:11

bruin

12-12-12, 13:30

I went to someones abode the other night to look at his bolt. My suspicions appear to be confirmed that the LMT enhanced bolt extractor springs appear to be ejector/selector springs that were cut into a 1/3.If this is true, then it would be possible to retrofit LMT enhanced bolts with stronger extractor springs. We need someone to measure the force of a standard 5-coil extractor spring plus black insert/O-ring, and figure out how long a pair of ejector springs need to be to duplicate that.

Or bug LMT to offer stronger enhanced bolt extractor springs, heh.

EzGoingKev

12-12-12, 18:19

Or bug LMT to offer stronger enhanced bolt extractor springs, heh.
What problems are you having with their enhanced bolt that you need stronger extractor springs to fix?

kenndapp

12-12-12, 19:17

after reading alot of threads on the enhanced bolt...... i too am concerned with the extractor tension. but this is coming from some one who drops a CS sprinco xp extractor spring into every bolt that crosses his path.

EzGoingKev

12-12-12, 19:19

after reading alot of threads on the enhanced bolt...... i too am concerned with the extractor tension.
Really? What threads?

kenndapp

12-12-12, 20:14

Really? What threads?
https://www.google.com/search?hl=en&newwindow=1&safe=off&tbo=d&rlz=1C1ASUT_enUS459US459&spell=1&q=lmt+enhanced+bolt&sa=X&ei=NDnJUOu5HMS20QGB8IHYCw&ved=0CDAQvwUoAA&biw=1366&bih=667

there is alot of them. been reading as much as i can. i cant remember exactly where. but some where, more than once, unimpressive extractor tension was observed by an end user.

this bolt had a real "lets see how far we can take the design" appeal to me. but starting to wonder if its worth the trouble.

EzGoingKev

12-12-12, 20:18

I am not looking for a google search, I wanted links to the specific threads with actual users talking about the problems they had or are having.

Waylander

12-12-12, 20:36

https://www.google.com/search?hl=en&newwindow=1&safe=off&tbo=d&rlz=1C1ASUT_enUS459US459&spell=1&q=lmt+enhanced+bolt&sa=X&ei=NDnJUOu5HMS20QGB8IHYCw&ved=0CDAQvwUoAA&biw=1366&bih=667

there is alot of them. been reading as much as i can. i cant remember exactly where. but some where, more than once, unimpressive extractor tension was observed by an end user.

this bolt had a real "lets see how far we can take the design" appeal to me. but starting to wonder if its worth the trouble.

He's not looking for help on Google but you to back up your claims with specific and verifiable testing where extractor tension has been an issue not just various ramblings on the internuts.

Two extractor springs in the lobster tail intentionally have less spring tension than one standard spring. This is supposed to lead to higher round count before spring failure since the two don't have to work as hard as one. It sounds like you and bruin have solutions in search of problems.

kenndapp

12-12-12, 20:57

He's not looking for help on Google but you to back up your claims with specific and verifiable testing where extractor tension has been an issue not just various ramblings on the internuts.

Two extractor springs in the lobster tail intentionally have less spring tension than one standard spring. This is supposed to lead to higher round count before spring failure since the two don't have to work as hard as one. It sounds like you have solutions in search of problems.

been searching through some of the threads and cant find my specific example. sorry.maybe they were just random internet ramblings.

Iraqgunz

12-12-12, 21:33

Have you looked at the enhanced bolt? The spring design is nothing like a standard extractor spring. There are two holes left and right rear (the "lobster" tail) and the springs for all intents and purposes look like the same spring for the selector and ejector.

We took an ejector spring and it was the exact same diameter and overall appearance as their extractor springs, but the difference being the size (length).

The next test will be to use the cut down ones and see if they work.

If this is true, then it would be possible to retrofit LMT enhanced bolts with stronger extractor springs. We need someone to measure the force of a standard 5-coil extractor spring plus black insert/O-ring, and figure out how long a pair of ejector springs need to be to duplicate that.

Or bug LMT to offer stronger enhanced bolt extractor springs, heh.

EzGoingKev

12-12-12, 21:35

I still want to know why he needs stronger springs.

sinlessorrow

03-01-13, 11:01

Bumping this with some new info. The new LMT Enhanced Carrier now has an extra 4th weep hole allowing the carrier to be used in rifles shorter than 14.5".

bruin

03-01-13, 11:21

Are you referring to the small hole on the curved face, behind the three lined-up vent holes?

sinlessorrow

03-01-13, 11:25

Are you referring to the small hole on the curved face, behind the three lined-up vent holes?

Yep, here is a pic for those who havent seen the new carriers.
http://i36.photobucket.com/albums/e30/VonCoz72/Picture001-2.jpg

DreadPirateMoyer

03-01-13, 11:50

sinlessorrow

03-01-13, 11:53

Any word on when these new carriers will be available? I'd love to get my hands on one for a suppressed LE6920 I'm putting together.

I wonder if I'll still need an extra strength action spring/H3 buffer...

Theyre shipping now but finding one in stock is the tough part.

I would say in a 14.5"-16" a H2 would be fine for these when suppressed.

DreadPirateMoyer

03-01-13, 12:04

Theyre shipping now but finding one in stock is the tough part.

I would say in a 14.5"-16" a H2 would be fine for these when suppressed.

Yeah, I can't find one in stock for the life of me, and I've been scrounging the intertubes daily for almost a month. :( Maybe it was good, though, so I didn't order the old model.

Crossin' my fingers from here on out.

sinlessorrow

03-01-13, 12:39

Yeah, I can't find one in stock for the life of me, and I've been scrounging the intertubes daily for almost a month. :( Maybe it was good, though, so I didn't order the old model.

Crossin' my fingers from here on out.

If you see one pop up I would grab it, by far the best BCG for the standard AR-15 short of something like the KAC E3 which requires a special barrel extension. Here is the email explaining what the hole does I got from LMT.

That is a weep hole designed to vent excess gas/pressure at a certain point during the cycle process. It was added to help reliability of the enhanced BCG with weapon systems shorter than 14.5”

saddlerocker

03-01-13, 14:04

Is the LMT Store the only place that offers the Carrier by itself?

Id like to avoid buying the whole BCG.

Ironman8

03-01-13, 14:14

FYI for those looking for one:

I put an order in for the Enhanced Carrier back in December (maybe it was earlier Jan) from LMT when they were showing in stock....of course I ended up backordered with all the madness, but I was told by LMT that they don't expect any new stock (for the E-Carriers) to be available until July 1st!

It will be interesting to see if I get the new one though...

sinlessorrow

03-01-13, 14:23

Is the LMT Store the only place that offers the Carrier by itself?

Id like to avoid buying the whole BCG.

I believe so but they are so backlogged they have online orderig disabled.

saddlerocker

03-01-13, 14:29

Maybe nothing, but rainier arms shows "returning soon" for the Enhanced BCG

sinlessorrow

03-01-13, 14:46

Is the LMT Store the only place that offers the Carrier by itself?

Id like to avoid buying the whole BCG.

I will also say, you do yourself a disservice by not gettin their enhanced Bolt as well. It was the only BCG to complete the PiP testing.

Iraqgunz

03-01-13, 15:06

I was told May a few weeks back so things are obviously changing.

FYI for those looking for one:

I put an order in for the Enhanced Carrier back in December (maybe it was earlier Jan) from LMT when they were showing in stock....of course I ended up backordered with all the madness, but I was told by LMT that they don't expect any new stock (for the E-Carriers) to be available until July 1st!

It will be interesting to see if I get the new one though...

Ironman8

03-01-13, 15:25

I was told May a few weeks back so things are obviously changing.

Well that's good news. Thanks for the update.

sinlessorrow

03-01-13, 15:34

I was told May a few weeks back so things are obviously changing.

Excellent news, I plan on picking one up when they come back.

sinlessorrow

03-01-13, 15:43

The bes parts of the bolt are the Carpenter AerMet material, the enhanced extractor with springs that are far less stressed than the standard spring, the relief cuts in the lugs as well as the slightly larger diameter at the base of the lugs, and this...the relieved lug opposite the extractor allowing for optimal loading of all lugs greatly reducing the stress of the lugs opposite the extractor where 90% of the AR-15 bolts break.

http://sgcusa.com/images/supporting_images_large/LMT_Enhanced_Full-Auto_Bolt_Carrier_Group_L7Q3_E.jpg

That combined with the Carrier that has a lengthened cam track allowing for longer lockup times allowing the chamber pressure to signifcantly drop, redesigned pas portin allowing pressure in the piston to be metered properly, which allows for proper acceleration of the carrier and also reduces fouling, as well as the sand cuts in the rails, and you have one of the best BCG's out there. Heres a good pic showin the cam track
http://www.impactguns.com/Data/Default/Images/uploads/darin_picures/Lewis_Machine__Tool/lmtbolt2.jpg

saddlerocker

03-01-13, 16:15

The reason I just want the carrier is due to the reports of malfunctions in sbr's.

I want it for a suppressed 11.5"

hotrodder636

03-01-13, 16:20

Subscribing to thread for tracking

sinlessorrow

03-01-13, 16:25

The reason I just want the carrier is due to the reports of malfunctions in sbr's.

I want it for a suppressed 11.5"

The only reports I have seen being negative were before the new carriers had the added weep hole designed to make them reliable with SBR's.

The bolt bydesign should not need any HD springs or O-rings because the design of the extractor itself should be more than enough even for an SBR.

Magic_Salad0892

03-01-13, 17:04

The only reports I have seen being negative were before the new carriers had the added weep hole...

No shit. Lol. Are there any reports of these working with SBRs? Or small port SBRs even?

I'm curious what difference one port makes.

sinlessorrow

03-01-13, 17:17

No shit. Lol. Are there any reports of these working with SBRs? Or small port SBRs even?

I'm curious what difference one port makes.

There are some on TOS...that said when guns run on milliseconds a extra weep hole like that can easily make the difference.

Magic_Salad0892

03-01-13, 18:14

There are some on TOS...that said when guns run on milliseconds a extra weep hole like that can easily make the difference.

Wait. So these are actually already out there?

sinlessorrow

03-01-13, 18:29

Wait. So these are actually already out there?

They came out last year, I just never saw them mentioned here. From what few reports I have found they seem to work in SBR's.

Magic_Salad0892

03-01-13, 18:34

They came out last year, I just never saw them mentioned here. From what few reports I have found they seem to work in SBR's.

Huh. I didn't even hear about them. Is there any chance you could post the TOS links to the info?

(BTW: It's pitiful that they have better technical threads about the Mk. 18, Mk. 12, and MEU(SOC) guns than we do.)

E-man930

03-01-13, 19:01

Gen 4 Carrier
http://www.impactguns.com/Data/Default/Images/uploads/darin_picures/Lewis_Machine__Tool/lmtbolt2.jpg

Gen 5 Carrier
http://i36.photobucket.com/albums/e30/VonCoz72/Picture001-2.jpg

(I'm going to post an update here in the near future showing all of the differences in the 5 generations of Enhanced carriers from LMT)

EzGoingKev

03-01-13, 19:04

What is the difference between the Gen4 and Gen5?

sinlessorrow

03-01-13, 19:04

Huh. I didn't even hear about them. Is there any chance you could post the TOS links to the info?

(BTW: It's pitiful that they have better technical threads about the Mk. 18, Mk. 12, and MEU(SOC) guns than we do.)

Here is a recent one, guy had his extractor springs break at 3,500 rounds but mentioned they had no problems running eve broke. I have heard similar of an incident with the KAC ones as well. Makes sense given the way the springs sit in the bolt.

F/A in a 10.5" with no issues.
http://www.ar15.com/forums/t_3_118/605299_LMT_Bolt_and_Carrier_Wear___10_11000_Rounds.html

Magic_Salad0892

03-01-13, 19:08

I wonder if the new carriers would allow the enhanced bolt to run in a small port 11.5''.

E-man930

03-01-13, 19:09

What is the difference between the Gen4 and Gen5?

Give me time to find, post, and label the pics... here is a quick answer.
The Gen 5s have 3 changes that I'm aware of over the 4s... Bearing surface reduction of the lower carrier bearings, dirt grooves around the changing handle notch no longer machined, and chrome lining after the weep hole is drilled. The surface finish was also changed from a rough textured park to a smooth park but it's not a mechanical change so I'm not really counting it.

E-man930

03-01-13, 19:12

Here is a recent one, guy had his extractor springs break at 3,500 rounds but mentioned they had no problems running eve broke. I have heard similar of an incident with the KAC ones as well. Makes sense given the way the springs sit in the bolt.

F/A in a 10.5" with no issues.
http://www.ar15.com/forums/t_3_118/605299_LMT_Bolt_and_Carrier_Wear___10_11000_Rounds.html

Sinless, that is the wrong thread...

BufordTJustice

03-01-13, 19:55

Yep, here is a pic for those who havent seen the new carriers.
http://i36.photobucket.com/albums/e30/VonCoz72/Picture001-2.jpg

That's exactly what my carrier looks like.

The last half of my Vltor A5/E-carrier thread was using the latest carrier. So all the info after I replaced the gen-1 applies to this one.

Sent from my SPH-D710 using Tapatalk 2

sinlessorrow

03-01-13, 20:22

Sinless, that is the wrong thread...

Correct thread. Read the reply from reefraider.

E-man930

03-01-13, 20:51

BufordTJustice

03-02-13, 00:53

sinlessorrow

03-02-13, 07:18

I wonder if these springs (with inserts) would run in an LMT bolt?

http://www.lwrci.com/p-224-acb-extractor-spring-kit.aspx#inf-tabs

Theyre not needed. The enhanced bolt generally doesnt break extractors, but you know darwin.

The fact that they still worked was great.

Magic_Salad0892

03-02-13, 07:47

Theyre not needed. The enhanced bolt generally doesnt break extractors, but you know darwin.

The fact that they still worked was great.

Reminds me of the HK P7 functioning without the extractor spring even installed.

Thomas M-4

03-02-13, 08:22

LMT has been slowly treaking the E-bcg since it has been released. First noticed this 2yrs ago when they changed some things on the bolt. (IMHO that is the proper way it should be done). I interested in hearing a good explanation how this modification is supposed to work.

E-man930

03-02-13, 09:28

I wonder if these springs (with inserts) would run in an LMT bolt?

http://www.lwrci.com/p-224-acb-extractor-spring-kit.aspx#inf-tabs

Yes they do...

E-man930

03-02-13, 09:29

Reminds me of the HK P7 functioning without the extractor spring even installed.

You mean functioning 100% without the extractor installed. ;)

sinlessorrow

03-02-13, 10:21

sinlessorrow

03-02-13, 21:41

any updates on the generation pics?

Sanpete

03-02-13, 23:58

Magic_Salad0892

03-03-13, 06:28

You mean functioning 100% without the extractor installed. ;)

That's what it was. I was gonna write that, but I didn't wanna be wrong. :o

AR15barrels

03-03-13, 11:14

I went to someones abode the other night to look at his bolt. My suspicions appear to be confirmed that the LMT enhanced bolt extractor springs appear to be ejector/selector springs that were cut into a 1/3.

I pulled out my inventory of enhanced bolt springs and extractors and measured them.
The coils appear to be closer together and the lmt springs are smaller diameters than all my selector detent springs.

15694

The long spring in the picture is a selector detent spring.
I have no doubt that you could shorten selector detent springs in a pinch and they would work fine.
The LMT springs I have do not appear to be the same as the selector detent springs that I have.

sinlessorrow

03-03-13, 12:34

One thing I reall like is how the LMT bolt uses the actual bolt to support the bottom of the case rim unlike the standard bolt that uses the extractor.

EzGoingKev

03-03-13, 12:36

chrome lining after the weep hole is drilled.

I thought LMT did not chrome the inside of their bolt carrier causing the TDP people to pee their pants?

Thomas M-4

03-03-13, 14:46

I thought LMT did not chrome the inside of their bolt carrier causing the TDP people to pee their pants?

We're did you get that? Mine is chrome lined .

EzGoingKev

03-03-13, 15:08

We're did you get that? Mine is chrome lined .
On various boards over the years.

If it is wrong then great, but to me it never made that bit of difference.

Thomas M-4

03-03-13, 15:12

On various boards over the years.

If it is wrong then great, but to me it never made that bit of difference.

The only uproar that I am a were of was the switch to MIM gas key.
Admitily I have not had the time I used to have on keeping up with this stuff.

EzGoingKev

03-03-13, 15:12

The only uproar that I am a were of was the switch to MIM gas key.
Yeah I remember that too.

Some people have stated their gas key screws were not staked but they came that way on the two I have.

Thomas M-4

03-03-13, 15:29

[QUOTE=EzGoingKev;1568439]Yeah I remember that too.

Some people have stated their gas key screws were not staked but they came that way on the two I have.[/QUOTE

Well you made me check mine out. Yes chrome lined but mine is the older version it came with forged chrome lined gas key also. Can't speak on current production.

Heavy Metal

03-03-13, 16:14

My two were staked, they just backed-out after 14K anyway.

Thomas M-4

03-03-13, 16:21

My two were staked, they just backed-out after 14K anyway.

Heavy metal can you confirm if LMT is or is not chrome lining the e-bcg any more ?

sinlessorrow

03-03-13, 16:47

I think your confused with the fact that LMT does no phosphate the barrel under the gas block.

E-man930

03-03-13, 18:08

Stop speculating!
I will update this post when I am able to find pics of the Gen 1 carriers... :ph34r:
>
*** MOVED TO THE TECHNICAL FORUM under LMT Enhanced Carrier Technical Comparison thread*** ==> https://www.m4carbine.net/showthread.php?p=1569875#post1569875

(this thread discusses the bolt)

Heavy Metal

03-03-13, 18:14

Heavy metal can you confirm if LMT is or is not chrome lining the e-bcg any more ?

Mine is an 05 model.

Magic_Salad0892

03-03-13, 18:42

I just realized that mine are Gen4s. I thought they were Gen2s. But they all have the weep hole.

How the hell did I never notice that?

How long have they been making the Gen4?

My old uppers ran the Gen2s for sure though. I bought those carriers in 2010.

MikeCLeonard

03-03-13, 18:59

Interesting photo-comparison...Thanks for posting that!

My E-Carriers appear to be Gen-5 in all regards except they don't look like they're using MIM Carrier keys...At least I can't see any little ring marks on the keys that are apparent on most MIM'd parts.

E-man930

03-03-13, 19:02

Heavy metal can you confirm if LMT is or is not chrome lining the e-bcg any more ?

All of their E-carriers are chrome lined, its the swap over to a non-chrome lined MIM gas key that confused everyone. The MIM key is hardened and does not benefit from the chrome lining.

sinlessorrow

03-03-13, 19:21

Thanks for the awesome comparison pic.

Cincinnatus

03-03-13, 21:05

All of their E-carriers are chrome lined, its the swap over to a non-chrome lined MIM gas key that confused everyone. The MIM key is hardened and does not benefit from the chrome lining.

Not all. I have one purchased in 2009 that is not chrome lined. About the same time people were debating the MIM key issue in a thread, it was also mentioned in a statement LMT put out that there was a proprietary coating on the inside of some of their, then, newer BCGs. To be clear, I mean the carrier itself is not chrome lined on this one, not just the gas key. I do not know what the coating is, but it looks black and not like plain parkerizing inside the carrier.

E-man930

03-03-13, 21:36

Interesting... can you post a pic?
I would like to see what version did not come with any chrome applied.

Cincinnatus

03-03-13, 22:11

Interesting... can you post a pic?
I would like to see what version did not come with any chrome applied.

http://i586.photobucket.com/albums/ss301/winfield813/image_zps0719a9ae.jpg
http://i586.photobucket.com/albums/ss301/winfield813/image_zps54c84d1c.jpg
http://i586.photobucket.com/albums/ss301/winfield813/image_zpse47a79df.jpg
http://i586.photobucket.com/albums/ss301/winfield813/image_zpsbe2a510c.jpg
http://i586.photobucket.com/albums/ss301/winfield813/image_zps6f3c8961.jpg
http://i586.photobucket.com/albums/ss301/winfield813/image_zpscb55e2a2.jpg

E-man930

03-03-13, 22:14

Thanks!
Can you post pics of the inside of the carrier? The "mouth" when you remove the bolt...

sinlessorrow

03-03-13, 22:44

Thanks!
Can you post pics of the inside of the carrier? The "mouth" when you remove the bolt...

+1, the tail of the carrier never has never been CL.

hjmpanzr

03-03-13, 22:46

Thanks!
Can you post pics of the inside of the carrier? The "mouth" when you remove the bolt...

I bought mine late 2008 and it appears exactly the same gen as Cincinnatus and mine is chrome lined inside the mouth. I can post photos tomorrow.

Cincinnatus

03-03-13, 22:51

The tail of the carrier is just parkerizing, I think. But the inside looks the same, just black. ( A darker color than parkarizing) I'll try to get another pick tomorrow of the inside of the bolt channel (where the proprietary lining is) after work.

Biggy

03-03-13, 23:00

Here are some pics of a new enhanced carrier I got from LMT around 9-3-12. The bolt is a new BCM from G&R Tactical.

http://i563.photobucket.com/albums/ss72/Biggy8/Picture120_zps6a44a0f5.jpg
http://i563.photobucket.com/albums/ss72/Biggy8/Picture121_zps111030bc.jpg
http://i563.photobucket.com/albums/ss72/Biggy8/Picture119_zps860f145f.jpg
http://i563.photobucket.com/albums/ss72/Biggy8/Picture026.jpg
http://i563.photobucket.com/albums/ss72/Biggy8/Picture025.jpg
http://i563.photobucket.com/albums/ss72/Biggy8/Picture021.jpg
http://i563.photobucket.com/albums/ss72/Biggy8/Picture022.jpg
http://i563.photobucket.com/albums/ss72/Biggy8/Picture023.jpg
http://i563.photobucket.com/albums/ss72/Biggy8/Picture027.jpg
http://i563.photobucket.com/albums/ss72/Biggy8/Picture024.jpg

BufordTJustice

03-04-13, 02:34

I've got a Gen 1 and a gen 4. My gen 4 looks the same as Biggy's above.

Cincinnatus

03-04-13, 15:45

Well, gents, I stand corrected.
I pulled the bolt out and took a look, and it turns out the bolt channel on this bolt IS chrome lined after all. I could have sworn on a stack of bibles that it was not. The gas key on this carrier is NOT chrome-lined and I think that that and the non-chromed tail ( as contrasted with a BCM carrier) is what I had in my mind before a wire got crossed somewhere. Too, the chrome lining on this one is recessed by the rounded rim of the carrier face, and not obvious. It is in the gas key on some that there is the black looking coating rather than chrome.
So, to conclude, yes, the insides of all the carriers are CL.

Magic_Salad0892

03-04-13, 16:23

So, the consensus is 100% that the newer Gen4/5 carriers will allow an Enhanced bolt to run in an SBR?

There was only that one account that I know of.

(My beater gun is at 4k, and I flip bolts every 5k. So I'm interested. Seems like I JUST rebarelled it, too.)

sinlessorrow

03-04-13, 16:24

Magic_Salad0892

03-04-13, 16:30

You mean you change bolts at 5k or break bolts at 5k? what gun is this?

The gun.

It started out as a 16.1'' SR-15 E3.

Cut it down to 11.1'' .071'' gas port, and cut the rail down too. (Did the rail myself actually.) I've had it for around 5 years. Ran it with an NT4.

Put 20k on it. Flipped the barrel (even though it was still grouping 3'' or so.) and because of that I had to change to Colt bolts too.

Right now it's running a regular 11.5'' Colt 6933 barrel because I managed to score one off of gunbroker on the cheap ($120. No shit.) and kept running it with the cut down URX, and NT4 (which still sounds great, by the way) and I've put about 4k on it since.

I'm gonna start flipping out bolts every 5k using USGI type bolts. (Suppressed, SBR, which is why.)

Which is why I'm interested in this bolt.

sinlessorrow

03-04-13, 16:36

The gun.

It started out as a 16.1'' SR-15 E3.

Cut it down to 11.1'' .071'' gas port, and cut the rail down too. (Did the rail myself actually.) I've had it for around 5 years. Ran it with an NT4.

Put 20k on it. Flipped the barrel (even though it was still grouping 3'' or so.) and because of that I had to change to Colt bolts too.

Right now it's running a regular 11.5'' Colt 6933 barrel because I managed to score one off of gunbroker on the cheap ($120. No shit.) and kept running it with the cut down URX, and NT4 (which still sounds great, by the way) and I've put about 4k on it since.

I'm gonna start flipping out bolts every 5k using USGI type bolts. (Suppressed, SBR, which is why.)

Which is why I'm interested in this bolt.

I would flip the bolt at 7K personally. Though according to LMT the weep hole was added to allow for proper use in a SBR, given their testing and numerous revisions I would say its a safe bet it will work.

5K is a bit early IMO for a standard bolt. There was a guy on TOS(hasnt posted in a while and pictures are gone) but they were running 7.5" suppressed guns and he mentioned they changed bolts and barrels every 4K.

Magic_Salad0892

03-04-13, 16:38

I would flip the bolt at 7K personally. Though according to LMT the weep hole was added to allow for proper use in a SBR, given their testing and numerous revisions I would say its a safe bet it will work.

Alright. I'll see if I can find one for sale. Hopefully I can burn 1k rounds by June, and see if it functions.

sinlessorrow

03-04-13, 16:39

Alright. I'll see if I can find one for sale. Hopefully I can burn 1k rounds by June, and see if it functions.

It seems like all this craze is slowing down so hopefully we will see things in stock again soon.

E-man930

03-04-13, 18:12

I moved the Carrier comparison to it's own thread in the technical section as not to further dilute this thread which is about the bolt. I'm tempted to make a bolt graphic much the same way as my carrier graphic since LMT has progressed through a few versions of the bolt...

BufordTJustice

03-04-13, 18:17

I moved the Carrier comparison to it's own thread in the technical section as not to further dilute this thread which is about the bolt. i'm tempted to make a bolt graphic much the same was as my carrier graphic since LMT has progressed through a few versions of the bolt...

Yes please on the bolt graphic. :)

E-man930

03-04-13, 18:18

Yes please on the bolt graphic. :)

HA!
I will just have to find the damn time... I'll rely on you guys to keep on me to get it done. No promises until at least the weekend though.

sinlessorrow

03-06-13, 11:05

HA!
I will just have to find the damn time... I'll rely on you guys to keep on me to get it done. No promises until at least the weekend though.

Dont forget!! Do you happen to have a high speed camera you could use to slow down and display the way it vents gas?

One thing to always remember is that these guns run on microseconds and those mucroseconds make a huge difference.

There is a 300 microsecond difference between when the gas hits the gas port between the M4 and M16, yet there is a 11,000 PSI difference(M4-26,000, M16-14,000) at the gas port, that 300 microsecond difference is why very few M16 bolts break vs the M4.

This carrier has an increased cam pin track which will give it a few hundred microseconds extra of dwell time before it begins to pull the case out of the chamber, those microseconds play a huge role in increasing reliability as they greatly drop chamber pressure and give the brass time to go back to normal size.

Then you have the enhanced porting of the BCG better controlling overgassing from the carbine system/suppressor greatly dropping pressure in the piston.

You combine far easier extraction, better pressure control, and the even distribution of stress to each lug thanks to the undercut lug opposite the extractor and you have a far more reliable BCG with far greater bolt life compared to the standard one.

Theres a reason why it completed the BCG PiP.

sinlessorrow

03-06-13, 13:33

Here is another interesting thing. Amphibian a member of TOS runs a 7.5" 7.62x39 AR and has broken every bolt outthere for 7.62 except one....the no longer made LMT enhanced 7.62 bolt. It is the only bilt he has never had break, oh and BTW he runs full auto. That says a lot, even LWRCI's bolt cracked at the lugs.

If the 7.62 variant can survive 7,000+ full auto 7.62x39, hust imagine their 5.56 variant.
http://www.c3junkie.com/m16/762/all.jpg

Here is a video showing how he runs his 7.62x39 AR....LMT the inly bolt to never break.
http://www.livevideo.com/video/24DB488D4B50482784F77C64CC254FAA/7-5-7-62x39-upper-w-mgi-modu.aspx

Magic_Salad0892

03-06-13, 13:58

sinlessorrow

03-06-13, 14:08

I wonder if the LMT bolt is similar in design to the KAC SR-47 bolt.

No idea, I have never seen the SR-47's bolt.
I do know LMT being the only bolt able to survive says a whole lot about the enhanced bolt.

sinlessorrow

03-08-13, 21:40

HA!
I will just have to find the damn time... I'll rely on you guys to keep on me to get it done. No promises until at least the weekend though.

Weekend time any updates?

BufordTJustice

03-22-13, 23:33

I'm gonna be a bitch and ask about an update. ;)

Tyrantresister

05-28-13, 13:24

Obscenejesster

05-28-13, 16:23

Is the LMT bolt made of 9310 or C-158?

sinlessorrow

05-28-13, 16:24

Is the LMT bolt made of 9310 or C-158?

carpenter Aermet. Its something like 2x stronger than C-158

Thomas M-4

05-28-13, 16:30

What things have been changed on the LMT enhanced bolt and when?

If my memory serves me there are 3 different gen of bcg. Some body posted a nice pictorial showing the differences. Sorry I don't have time to dig them up or post a link fixing to go to work.
Maybe some body will be nice enough to post a link to the pics.

Obscenejesster

05-28-13, 16:53

carpenter Aermet. Its something like 2x stronger than C-158

I've also head 9310 is a little stronger than C-158. Do you know if that's true?

Tyrantresister

05-28-13, 17:00

I've heard that, but also read that it's just a rumor, and it's actually more brittle than C-158.

I know there have been multiple gens of the carrier, but what has changed with the bolt itself?

sinlessorrow

05-28-13, 17:07

I've heard that, but also read that it's just a rumor, and it's actually more brittle than C-158.

I know there have been multiple gens of the carrier, but what has changed with the bolt itself?

Small things like bolt coating and lug reliefs.

Tyrantresister

05-28-13, 17:16

Oh, the coating wasn't always electroless nickel? Or it isn't electroless nickel anymore?

Iraqgunz

05-28-13, 18:37

Do you know 100% for a fact that LMT is using Aermet 100 for their bolts?

carpenter Aermet. Its something like 2x stronger than C-158

sinlessorrow

05-28-13, 18:56

Do you know 100% for a fact that LMT is using Aermet 100 for their bolts?

Im not sure what grade Aermet since I belive there are different ones but in an email from LMT, yes they use Aermet. Thy did not specify. I asked if it was aermet and they confirmed, but that was all I got fromthe person I talked to.

This was awhile so, so things could have changed but last i heard.

Eta: that is just the enhanced bolts. Their standard are not aermet.

Iraqgunz

05-28-13, 19:09

If it's Aermet then it is more than likely Aermet 100. I wasn't aware that they were doing anything other than Carpenter 158.

Im not sure what grade Aermet since I belive there are different ones but in an email from LMT, yes they use Aermet. Thy did not specify. I asked if it was aermet and they confirmed, but that was all I got fromthe person I talked to.

This was awhile so, so things could have changed but last i heard.

Eta: that is just the enhanced bolts. Their standard are not aermet.

Obscenejesster

05-28-13, 19:13

Do the LMT bolts last? If they last as long or longer than other bolts, they could be made out of polymer for all I care.

That being said, I'll just stick with BCM BCG's for my daily drivers. I wouldn't mind having back up BCG's made by other manufactures though. I do have a BCG from Joe Bobs that uses a bolt made of 9310 but that is currently just a back up.

mtdawg169

05-28-13, 19:25

If it's Aermet then it is more than likely Aermet 100. I wasn't aware that they were doing anything other than Carpenter 158.

Is this what KAC is using also?

E-man930

05-28-13, 19:40

Name a time an A100 bolt failed outside of lab testing?

Iraqgunz

05-28-13, 19:43

You should probably do a little research first.

Do the LMT bolts last? If they last as long or longer than other bolts, they could be made out of polymer for all I care.

That being said, I'll just stick with BCM BCG's for my daily drivers. I wouldn't mind having back up BCG's made by other manufactures though. I do have a BCG from Joe Bobs that uses a bolt made of 9310 but that is currently just a back up.

Obscenejesster

05-28-13, 20:06

You should probably do a little research first.

Without doing the research, I guess you're saying LMT bolts are prone to failing? Okay then. Now I know what bolt I won't be buying in the future.

eperk

05-28-13, 20:28

Without doing the research, I guess you're saying LMT bolts are prone to failing? Okay then. Now I know what bolt I won't be buying in the future.

LMT makes excellent bolts.

Heavy Metal

05-28-13, 20:35

Without doing the research, I guess you're saying LMT bolts are prone to failing? Okay then. Now I know what bolt I won't be buying in the future.

He isn't saying anything of the sort.

E-man930

05-28-13, 20:42

Without doing the research, I guess you're saying LMT bolts are prone to failing? Okay then. Now I know what bolt I won't be buying in the future.

What a waste of thread space...

Iraqgunz

05-28-13, 20:57

No. What I am saying is that LMT bolts and carriers are good to go. I like BCM too, but they aren't the only game in town. If you read about the properties of Carpenter 158 and Aermet you will see that they are both very good alloys.

Without doing the research, I guess you're saying LMT bolts are prone to failing? Okay then. Now I know what bolt I won't be buying in the future.

sinlessorrow

05-28-13, 21:18

Obscenejesster

05-28-13, 21:20

No. What I am saying is that LMT bolts and carriers are good to go. I like BCM too, but they aren't the only game in town. If you read about the properties of Carpenter 158 and Aermet you will see that they are both very good alloys.

Oh, I understand there are other BCG's of equal or maybe even better quality than BCM. It's just what I own and what I know. I just look at it in the fact that I haven't had one fail me yet so why change.

I haven't really done any research on Aermet but I have done some on 9310 and from what I've found, it looks like 9310 could be stronger than C-158 as long as it was heat treated properly.

Artos

05-29-13, 09:03

DreadPirateMoyer

05-29-13, 12:52

Does anyone run these suppressed? I'll be running one in a DD 16" middie both suppressed and unsuppressed, and I'd be interested in hearing how the bolt performs with excess gas pressure.

As combared to carbines and SBRs that we know the bolt works in, the middie will have a lower unsuppressed gas pressure by its very nature, while the suppressor will add some pressure, which leads me to believe they may roughly cancel out with regards to the bolt's performance (especially with the extra venting provided by the enhanced carrier). AKA: it seems like the bolt would be operating at a similar pressure to an SBR or carbine on a suppressed middie.

Can anyone confirm/deny, or tell me if I'm being stupid in my thinking?

Ironman8

05-29-13, 13:43

Sorry to switch gears.

Has LMT been cranking out enhanced bolt carriers?? I'm using Grant's small gas port set up with the enhanced group, but with the standard bolt.

No big hurry & just wondering if they are running at capacity and/or behind & trying to keep up like everyone else in the industry right now. Time to get an extra pretty soon & thought someone here may have the skinny.

I've been on backorder for one since about January. I haven't called recently to check on my order, but the last thing I was told was that it would be around July. Apparently some were told sooner IIRC.

I have seen some complete E-BCGs come in stock a couple of places, but no order complete confirmation for me....so not sure what that's about...

ETA: See page 4 starting with my post #71...I was told July, IG was told May. Anybody get theirs yet?

DreadPirateMoyer

05-29-13, 14:01

I got 2 from SGC in the last month. Not sure where they're getting their stock from, though. Some came in stock today, in fact.

Thomas M-4

05-29-13, 15:46

Here is the link comparing the different gen bcg.
Actually there is more than 3 different gens.

https://www.m4carbine.net/showthread.php?p=1617133

Pappabear

05-29-13, 17:01

It works as well as any other Bolt. I've used mine in every configuration with no issues.

DreadPirateMoyer

05-29-13, 17:23

It works as well as any other Bolt. I've used mine in every configuration with no issues.

Thanks Pappabear. That include suppressed? Without an adjustable block?

Pappabear

05-29-13, 18:24

That is correct. M4-2000 and AAC MINI4
No issue , use with confidence

DreadPirateMoyer

05-29-13, 18:47

That is correct. M4-2000 and AAC MINI4
No issue , use with confidence

Awesome. Thanks Pappa.

Pappabear

05-29-13, 20:54

I think the bolts are great. Both LMT and KAC have similar designs and you can build a better mousetrap. I dont think its necessary but its good to have. I heard that the opposing lug could break off, never heard of it till I watched Pat Rogers video spoke of it and may have shown one on the video.

To have a bolt with the finish alone is worth the cost of the bolt. The only downside is the parts to repair are proprietary. I wish the extractor was mil spec so repairing was just like any other.

the_1iviper

05-29-13, 23:04

markm

05-30-13, 12:09

You won't find one of these hipster doo-dads in any of my guns.

AR15barrels

05-30-13, 12:12

would the enhanced bolt be good to use in a 300blk build ? the barrel is a noveske 8.2"

i was lucky enough to pick one of the enhanced BCG's up from SGC today. i've been looking for a bolt for my 300blk build but figured i could use the carrier in my 11.5" 5.56 gun and the bolt for the 300blk.

I would NOT use the LMT enhanced carrier in a 300 blackout build due to the carrier being optimized for higher gas pressures.
The bolt would be fine though.

I don't know that I would recommend the LMT enhanced carrier in a 11.5" carbine gassed 5.56 either.
Those carriers were specifically made to help 14.5" amd 16" carbine gassed 5.56 guns.

Ironman8

05-30-13, 12:20

I would NOT use the LMT enhanced carrier in a 300 blackout build due to the carrier being optimized for higher gas pressures.
The bolt would be fine though.

I don't know that's would recommend the LMT enhanced carrier in a 11.5" carbine gassed 5.56 either.
Those carriers were specifically made to help 14.5" amd 16" carbine gassed 5.56 guns.

On a suppressed SBR, they seem to run great. I'm running one in my 11.5" and Grant runs one in his 10.5".

Small gas port and H3 buffer as well. Super smooth cyclic action.

Tyrantresister

05-30-13, 12:24

You won't find one of these hipster doo-dads in any of my guns.

That's why I refuse to use a flattop (or optic, or anything battery powered)!

AR15barrels

05-30-13, 12:25

On a suppressed SBR, they seem to run great. I'm running one in my 11.5" and Grant runs one in his 10.5".

Small gas port and H3 buffer as well. Super smooth cyclic action.

A suppressor effectively lengthens the barrel by about 3", so that makes sense.
My recomendation of not using them on short barrels was an "unqualified" recommendation, meaning that all factors are considered and the recommendation stands on its own and is accurate for anyone reading it.
If you add a suppressor into the mix, that "qualifies" the discussion to only apply to people with suppressors, but you are correct that they would work good in that specific situation.

Tyrantresister

05-30-13, 12:27

Here is the link comparing the different gen bcg.
Actually there is more than 3 different gens.

https://www.m4carbine.net/showthread.php?p=1617133

Ok, so there have been changes between the CARRIERS, but the BOLTS THEMSELVES have stayed the same?

Ironman8

05-30-13, 12:33

A suppressor effectively lengthens the barrel by about 3", so that makes sense.
My recomendation of not using them on short barrels was an "unqualified" recommendation, meaning that all factors are considered and the recommendation stands on its own and is accurate for anyone reading it.
If you add a suppressor into the mix, that "qualifies" the discussion to only apply to people with suppressors, but you are correct that they would work good in that specific situation.

Absolutely. Hope you didn't take my statement as argumentative. I know you know your stuff ;)

Iraqgunz

05-30-13, 13:13

Understand on the .300 BLK. However, the enhanced carrier does in fact work very well on SBR's with no negative effects thus far. Especially when being fired suppressed.

I would NOT use the LMT enhanced carrier in a 300 blackout build due to the carrier being optimized for higher gas pressures.
The bolt would be fine though.

I don't know that I would recommend the LMT enhanced carrier in a 11.5" carbine gassed 5.56 either.
Those carriers were specifically made to help 14.5" amd 16" carbine gassed 5.56 guns.

sinlessorrow

05-30-13, 13:39

Ok, so there have been changes between the CARRIERS, but the BOLTS THEMSELVES have stayed the same?

LMT has gone through a few different coating and lug relief designs.

the_1iviper

05-30-13, 15:37

I would NOT use the LMT enhanced carrier in a 300 blackout build due to the carrier being optimized for higher gas pressures.
The bolt would be fine though.

I don't know that I would recommend the LMT enhanced carrier in a 11.5" carbine gassed 5.56 either.
Those carriers were specifically made to help 14.5" amd 16" carbine gassed 5.56 guns.

thanks for the reply. i'll only be using the bolt , the stock set up i'm using uses a proprietary carrier. i guess i'll just hang onto the carrier for testing purposes ;)

the_1iviper

05-30-13, 15:40

Understand on the .300 BLK. However, the enhanced carrier does in fact work very well on SBR's with no negative effects thus far. Especially when being fired suppressed.

this is good to hear. i'll be testing the 300blk upper on several lowers so i'll be sure to try the whole BCG also.

BufordTJustice

05-31-13, 17:43

Understand on the .300 BLK. However, the enhanced carrier does in fact work very well on SBR's with no negative effects thus far. Especially when being fired suppressed.

+1

I understand what Randall said about higher gas pressures, and that may well have been LMT's original design goal...but the LMT e-carrier clearly does not need higher-than-normal gas pressures to function.

IG, you've seen my comments on my 14.5" middy BCM with an LMT e-carrier and Vltor A5H4 buffer.....the gun shouldn't run, but it does. I know your experiences mirror my own in large part.

Tyrantresister

09-01-13, 18:56

Was comparing two of my LMT Enhanced Bolt's and noticed some strange differences.

While at a quick glance, they look the same, closer inspection showed a few subtle details.

The relief cuts for the lugs were in different places (one had the cuts closer to the bottom of the lug, while the other had the relief cut in the center of the lug)

One is stamped as being "MP" while the other one isn't (both are MP'd but one doesn't advertise it)

One has the letter G stamped on it. The other has the letter S stamped on it.

Does anyone know the nature / reason for these differences along with rough gen # / manufacture date? I assume one is obviously a newer (better?) gen. Not sure why those subtle differences make one that much better.

Anyone have any info / insight on this? Check out the pictures below!!!

https://lh3.googleusercontent.com/-FLj4SwTEPxM/UiO_NX4jS1I/AAAAAAAAA8w/mzLZX0gLAjg/w889-h500-no/2013-09-01_18-02-12_372.jpg
Note the differences in relief cuts, plus one being marked "MP"

https://lh6.googleusercontent.com/-0d809cuhVuk/UiO_P_AmY_I/AAAAAAAAA88/1fjv9M-h-pE/w889-h500-no/2013-09-01_18-05-15_196.jpg
One is stamped "S"
One is stamped "G"

Any ideas???

ABNAK

09-01-13, 20:31

Is one older than the other? The bottom one with the more rearward relief cut is what I have (bought it maybe 1 or 2 years ago). I'll have to check the markings later.

I know the carriers themselves had gone through a few "generations" but wasn't aware the bolts had.

Tyrantresister

09-02-13, 14:59

Check the markings?

sinlessorrow

09-03-13, 08:30

Top is the newest, bottom is their older design.

Tyrantresister

09-03-13, 21:25

Lots of conflicting reports here!

og556

09-03-13, 23:20

Just wanted to add a little info about what an LMT employee told me about the Enhanced BCG.

1. This BCG should be fine for any mid length 16" or longer barrel. When it was originally designed it was optimized for 14.5" Carbine length gas weapons but according to LMT this BCG is GTG on mid length gas carbines.

The gentleman I spoke to also mentioned to call them and ask for help if there are any kinds of issues with this BCG in a middy. The willingness to help if there are any issues is refreshing.

2. If you are looking for spare extractor springs for this BCG they advised to contact them directly by phone to order some.

I have one of these BCG's on the way and wanted to test it with one of my 16" mid length Noveske carbines with an A5 equipped lower. If the carrier does not work out in this config I may end up selling it.

Iraqgunz

09-03-13, 23:54

I have tested it in several configs and it is working fine thus far.

Just wanted to add a little info about what an LMT employee told me about the Enhanced BCG.

1. This BCG should be fine for any mid length 16" or longer barrel. When it was originally designed it was optimized for 14.5" Carbine length gas weapons but according to LMT this BCG is GTG on mid length gas carbines.

The gentleman I spoke to also mentioned to call them and ask for help if there are any kinds of issues with this BCG in a middy. The willingness to help if there are any issues is refreshing.

2. If you are looking for spare extractor springs for this BCG they advised to contact them directly by phone to order some.

I have one of these BCG's on the way and wanted to test it with one of my 16" mid length Noveske carbines with an A5 equipped lower. If the carrier does not work out in this config I may end up selling it.

Fgolebiowski

09-04-13, 01:46

We have been running an LMT Enhanced Full Auto Bolt Carrier Group in an LMT 16” barrel CQB (Close Quarter Battle) MRP™ Receiver Group with Mil-Spec carbine action spring and H3 buffer lubricated with Slip 2000 EWL (Extreme Weapons Lubricant) with total reliability using quality factory .223 and 5.56 ammunition.

BTL BRN

09-04-13, 08:56

I should be getting my tax stamp somewhere around November, at which time I plan on using mine in a factory MK18 upper; if whatever internet conjecture regarding the gas port size is valid, the enhanced carrier/bolt should help to alleviate that.

og556

09-04-13, 09:10

Just so you guys know Scottsdale gun club has an amazingly good price on the Full Auto Enhanced BCG.

AR15barrels

09-04-13, 11:51

cspackler

09-04-13, 12:48

My lmt bcg has functioned flawlessly in a 16" DD carbine gas upper. I have the bolt version like the one on top in the pic (except it is marked R instead of S). I just ran a cpl hundred more without prior cleaning (been maybe 1k rounds) and a small dose of slip2k. I have a surefire mb556 attached and it's on a lower with the mgi buffer. Very soft recoil and little muzzle rise but it never chokes - even with Silver Bear.

556hollowtip

09-07-13, 00:40

I'll add some to the mix.
Both M16 carriers and enhanced.
Top one was purchased back in 08 i believe.
Bottom one was last month.
http://i581.photobucket.com/albums/ss256/556hollowtip/LMT%20Bolt%20Carrier/IMG_3851.jpg

Top is old and is marked with MP and letter U
Bottom is not marked MP and has letter L
http://i581.photobucket.com/albums/ss256/556hollowtip/LMT%20Bolt%20Carrier/IMG_3858.jpg
Old one has relief cuts on the back of the lugs and new one doesn't.

Two more with different focus.
http://i581.photobucket.com/albums/ss256/556hollowtip/LMT%20Bolt%20Carrier/IMG_3855.jpg
http://i581.photobucket.com/albums/ss256/556hollowtip/LMT%20Bolt%20Carrier/IMG_3854.jpg

sinlessorrow

09-07-13, 00:46

556hollowtip

09-07-13, 00:48

Those aren't relief cuts, they are lead in cuts. Lots of bolts have those.

Good to know. Thanks

halmbarte

09-07-13, 02:49

The stress relief cut is the ring cut behind the lugs. That reduces the stress riser the transition from the bolt body to the locking lugs creates.

Compare to a SCAR bolt, for example.

https://lh5.googleusercontent.com/-goJrx3b9YL4/UirZpztvftI/AAAAAAAAG0A/1u_5T2qmihg/w380-h231-no/scar+bolt.jpg

Here's another bolt that's using dual extractor springs.

https://lh4.googleusercontent.com/-DcE6VZUvNwE/UA-MW8f0M3I/AAAAAAAAD-c/46ZF_s8e0dw/w722-h654-no/IMG_1123.JPG

H

Mall_Ninja

09-08-13, 03:25

http://i581.photobucket.com/albums/ss256/556hollowtip/LMT%20Bolt%20Carrier/IMG_3854.jpg

Broken lug on the bottom bolt?

Lawnchair 04

09-08-13, 07:48

Broken lug on the bottom bolt?

Nope they come that way from LMT. I though it was weird too when I pulled apart my enhanced bcg.

556hollowtip

09-08-13, 10:10

That lug is directly opposite of the extractor. I believe it's something to do with allowing the bolt to fully support the case.

Pappabear

09-08-13, 17:25

halmbarte

09-09-13, 01:06

There is also some pressure issue with that lug mostly likely to get broken and it relives pressure....it is intentional and goes way beyond my thought process.

I think there is reference to it from the guy who wrote a dissertation on the LMT BCG and Bolt on here at one point. Great write up.

Also, I saw on one of the throw away BCM videos they give when you order stuff from BCM, (that old scruffy guy ex cop) went through issues and showed some broken lugs on BCG's. I thought to myself, ah LMT knows what they are doing.

The lug opposite the extractor takes the worse beating and this makes it more balanced , less stressed on the BCG.

Thats the best I got and something that confuses me. :D

The two lugs on either side of the extractor take the most load dutring firing because of the missing lug where the extractor is.

Relieving (or removing) the lug opposite the extractor balances the load better among the remaining 6 lugs. Or, you could design a bolt with 6 lugs, like the picture of the bolt above with the 2 extractor springs.

H

Mall_Ninja

09-09-13, 14:58

Relieving (or removing) the lug opposite the extractor balances the load better among the remaining 6 lugs.

How exactly?

kaltesherz

09-09-13, 18:39

Has anyone managed to locate an Enhanced Carrier WITHOUT the bolt? I've been looking for one forever and all I can find are complete EBCG's...

Iraqgunz

09-09-13, 18:45

Good luck. I ordered mine in December and they arrived in June.

Has anyone managed to locate an Enhanced Carrier WITHOUT the bolt? I've been looking for one forever and all I can find are complete EBCG's...

kaltesherz

09-09-13, 18:47

Good luck. I ordered mine in December and they arrived in June.

Well, if things continue as they have if I order one now I'll get it around the time the ATF approves my Mini4.

Where did you back-order it?

Iraqgunz

09-09-13, 19:15

LMT directly.

Well, if things continue as they have if I order one now I'll get it around the time the ATF approves my Mini4.

Where did you back-order it?

Blankwaffe

09-09-13, 23:14

There is also some pressure issue with that lug mostly likely to get broken and it relives pressure....it is intentional and goes way beyond my thought process.

I think there is reference to it from the guy who wrote a dissertation on the LMT BCG and Bolt on here at one point. Great write up.

Also, I saw on one of the throw away BCM videos they give when you order stuff from BCM, (that old scruffy guy ex cop) went through issues and showed some broken lugs on BCG's. I thought to myself, ah LMT knows what they are doing.

The lug opposite the extractor takes the worse beating and this makes it more balanced , less stressed on the BCG.

Thats the best I got and something that confuses me. :D

Yeap,the relieved lug design principle has been in use for awhile. Armalite has been using the relieved lug "improved rifle bolt" design as standard since the mid to late 90's on the AR10 and M15 bolts.

Here is the tech note description.

http://www.armalite.com/images/Tech%20Notes/Tech%20Note%2013,%20Improved%20Rifle%20Bolt%20960507.pdf

halmbarte

09-10-13, 01:09

How exactly?

From the Armalite paper above:

1. ArmaLite® bolts bear 7 locking lugs, each 22.5 degrees apart from the next. At this angle there should be 8 lugs in a circle, but one lug has been removed to provide space for the extractor.

2. The missing lug creates an asymmetry, or imbalance, in the bolt. When the rifle is fired the pressure of the cartridge presses the bolt rearward, and the lugs transfer this energy to the matching locking lugs of the barrel extension. The bolt flexes at the rear inside corner of the lug during this process. Because one lug is missing, the deformation is greatest in the area of the missing bolt. A series of engineering analyses have disclosed that the lugs on either side of the extractor each receive 40% of the recoil load.

3. Relieving the rear of the lug opposite the extractor "balances" the loading of the bolt by restoring symmetry. The load placed on the bolt is spread more evenly over the six remaining lugs. Peak lug loading is reduced.
4. Relieving the lug opposite the extractor reduces peak loading on the lugs neighboring the extractor from 40% to 24% each. It is not reduced to 16 1/3% (1/6 of the recoil load) because a small asymmetry remains: the lugs neighboring the extractor are slightly undercut for the extractor, which results in continued relative weakness at those lugs.
Nonetheless, the load on the weakest lugs is reduced 40%, compared to the standard M-16 design, by spreading a portion of that load to the other 4 lugs.

H

Mall_Ninja

09-10-13, 13:09

From the Armalite paper above:

H

Yeah I have seen that. But it describes something quite different than what the LMT pic above depicts...Almost opposite, as the LMT is "relieved" in the front and still has a rearward lug contact area?

Blankwaffe

09-10-13, 18:16

I don't have a LMT Enhanced bolt in hand,and haven't talked to LMT about the lug design in that regard.But from what Ive read from Bill Alexander and other Industry Professionals the LMT and Armalite bolt lug modifications reach the same basic theory.Just two different patented designs/techniques.Obviously the LMT Enhanced bolt features a much more intricate design with many more features.
LMT's standard bolt design using relieved lug root is solid engineering from what Ive heard from the Mechanical Engineer's(several) around me.

og556

09-10-13, 21:13

I put 150 rounds through my rifle with the following specs today:

Upper
- Noveske factory assembled N4 Light Mid Length Chrome Lined with NSR
- KAC MAMS 5.56 Brake

Lower
- LMT Lower Receiver
- VLTOR A5 Receiver Extension with green springco spring

Magazines
- 3 very old PMAGs pre rev M with windows. Unknown round count but I have been using them for the last 7 years as my primary range mags.
- 1 old bushmaster metal 30 round magazine. Very old and unknown round count.

I know 150 rounds is practically nothing but the range I was planning on going to was closed today so I ended up at another place which only goes out to 22 yards. I wanted to shoot this today to figure out how it feels and whether this BCG is reliable with this configuration.

I first ran two 30 round magazines of PMC 55gr which cycled flawlessly and had no issues out of two old PMAGs that I have.

I then continued to load and shoot 60 rounds of 55gr tula ammo which cycled and locked back without issue.

The remainder of the ammo was loaded and shot between 2 and 5 rounds a magazine to verify it cycles and locks back. It was all PMC 55gr and ran without any issues.

Tomorrow I plan on putting 240 rounds through it. I wont be cleaning this rifle for at least 1k rounds to find out how this BCG does dirty.

So far it seems like a good choice although very expensive. After reading IraqGunz's post on his experience with this BCG I am not surprised it ran.

Mall_Ninja

09-11-13, 00:58

- VLTOR A5 Receiver Extension with green springco spring

So just to be sure, you are using the LMT enhanced bolt AND carrier?

Which Vltor buffer?

E-man930

09-11-13, 09:29

I second that...
Looks like you posted in the wrong thread, this one is about LMT E-bolts, not the carrier...

og556

09-11-13, 23:44

Yes I am using the entire LMT Enhanced Bolt Carrier Group including the enhanced bolt. As far as I can tell it is a newer version. The bolt is marked "AE" and MPI. I'm not sure what AE stands for. The Vltor Buffer I am using is the standard A5H2 5.3oz buffer.

I fired the remaining 240 rounds of PMC through my rifle at the NRA range today and had absolutely zero malfunctions or failures to lock back. I must emphasize that this particular setup is the most flat shooting AR 15 I have ever handled.

The only finding I discovered is that when I brought it home I disassembled the BCG to inspect the internals. I noticed the cam pin had quite a bit of wear for so few rounds through it. I reassembled the BCG without cleaning but I did add some more fireclean clp.

I should also mention that upon receiving the LMT E-BCG I noticed that there are some deep machining marks or scratches on the face of the lugs of the bolt. At first I was concerned and contacted LMT whereupon a gentleman informed me that since they do machine cut these bolts and do not phosphate coat them I may notice machining marks like the ones I describe but they should be fine. I will keep an eye on the marks on the bolt lugs I'm sure LMT will stand behind their product if issues arise.

I apologize if my posts are not pertinent to this thread. I was simply trying to report my experiences the LMT Enhanced bolt and carrier group with my particular setup which according to some folks should not run.

Moderators if the content of my posts are out of place for this thread pertaining to the LMT enhanced bolt please delete them at your discretion.

I will report after I have over 1,000 rounds with this particular setup without cleaning in a separate thread.

Again I do apologize if my posts are not relevant to this topic please feel free to delete them.

Mall_Ninja

09-12-13, 00:41

Moderators if the content of my posts are out of place for this thread pertaining to the LMT enhanced bolt please delete them at your discretion.

Rest assured, the mods delete with the quickness around here. If they wanted your post gone it would have been within seconds...

In fact, you may only read this in your email notification... lol :D

og556

09-12-13, 00:49

Haha thanks buddy. My only goal here is to learn and contribute any useful info when I can. Definitely not trying to stir any stuff up. I enjoy this community.

EzGoingKev

09-12-13, 09:07

The only finding I discovered is that when I brought it home I disassembled the BCG to inspect the internals. I noticed the cam pin had quite a bit of wear for so few rounds through it. I reassembled the BCG without cleaning but I did add some more fireclean clp.

I have (2) LMT enhanced bolt carriers and found this as well.

I attribute this to the sharp angle of the revised cam pin channel. I am hoping that they will smooth out as the round count climbs.

og556

09-12-13, 10:09

Yea I'm not too worried at this point but it is different from what I'm used to.

Mall_Ninja

09-12-13, 18:04

Yea I'm not too worried at this point but it is different from what I'm used to.

Its LMT bro, no reason to be "worried" at any level! :D

BufordTJustice

09-22-13, 10:09

I have (2) LMT enhanced bolt carriers and found this as well.

I attribute this to the sharp angle of the revised cam pin channel. I am hoping that they will smooth out as the round count climbs.

I've found using an NiB cam pin negates much of the wear. LWRC probably has the cheapest for about $11. Mine is either a Fail Zero or a Spikes (can't remember). It has very little wear on it after several thousand rounds. Also, I lube with Aeroshell #7 synthetic EP aircraft grease, so I'm sure that helps as well.

EzGoingKev

12-19-13, 18:26

I've found using an NiB cam pin negates much of the wear. LWRC probably has the cheapest for about $11. Mine is either a Fail Zero or a Spikes (can't remember). It has very little wear on it after several thousand rounds.

I am running some Colt ones and have a bunch of BMC replacements. I want to run them some and knock down the sharp edges and then send the bolt carriers out to Robar to get one of their NP3 coatings done. The only thing I am concerned with is the small bleed hole getting blocked during the coating.

Has anyone had their enhanced carriers plated?

On another note, I received (3) new enhanced bolt carriers from LMT yesterday. First off the finish is now smooth. The last ones I got had a rough/textured finish. Some of the machine work seems to be more refined also.

https://lh5.googleusercontent.com/-gyGHsAuYav0/UrOLhmQDusI/AAAAAAAAG0o/UskmbVj363w/s800/LMT_Enhanced_Bolt_FA_005.jpg

https://lh6.googleusercontent.com/-9j0ndHdmbw4/UrOLjZTR1EI/AAAAAAAAGz8/ZROOnayAbBc/s800/LMT_Enhanced_Bolt_FA_008.jpg

They are still using the (3) main holes, (1) tiny hole, and then the 4th hole -
https://lh4.googleusercontent.com/-zOxMNDOm8-4/UrOLiGxcKqI/AAAAAAAAGz0/KI8Tmlvwpws/s800/LMT_Enhanced_Bolt_FA_004.jpg

Gas key is staked. Allen heads are somewhat stripped out, wish they used a better quality bolt. I do not believe this to be a MIM key as it does not have the mold marking -
https://lh3.googleusercontent.com/-QYIp2ZGLwAo/UrOLmT_SpII/AAAAAAAAG0U/bhiclmpAvoY/s800/LMT_Enhanced_Bolt_FA_009.jpg

Chrome lined bore -
https://lh6.googleusercontent.com/-GW7j-NYuY7Q/UrOLfgLIG-I/AAAAAAAAGzk/NqlQ-0NX_nQ/s800/LMT_Enhanced_Bolt_FA_003.jpg

Cam tunnel -
https://lh5.googleusercontent.com/-SUAmrgY7BjQ/UrOLezw-JgI/AAAAAAAAGzg/oixnU82y0GI/s800/LMT_Enhanced_Bolt_FA_002.jpg

DreadPirateMoyer

12-20-13, 17:17

Might still be a MIM key, just with the mark somewhere not visible.

Also, LMT's constant, unannounced iterations to these things breaks my heart. I feel like I'm buying electronics that get outdated in 6 months.

556Cliff

12-20-13, 17:41

Kev,

Do all three of the Enhanced carriers you received have stripped out gas key screws, or are they only stripped out on the one pictured?

Also, are the gas keys chrome lined?

EzGoingKev

12-20-13, 19:17

Kev,

Do all three of the Enhanced carriers you received have stripped out gas key screws, or are they only stripped out on the one pictured?

Also, are the gas keys chrome lined?
I bought (3) of them, (1) for me and (2) are for friend. They are all full auto carriers. I just grabbed one out of the box for myself and that was the one I took the pics of.

Top to bottom, (1) two year old SA enhanced carrier, (2) brand new FA enhanced carriers. Note the difference in texture -
https://lh3.googleusercontent.com/-KMwOglk_7Xo/UrTpj5Wza_I/AAAAAAAAG2M/kHGazKUPGEw/s800/20131220_193921.jpg

The gas key bolts on these are not stripped out like the other one -
https://lh5.googleusercontent.com/-GtdyskvWL6M/UrTpkR3_K6I/AAAAAAAAG2U/BKXBDjUu0xM/s800/20131220_193936.jpg

https://lh5.googleusercontent.com/-6iOzKzfqDPA/UrTpkTRzFCI/AAAAAAAAG2Q/MO3IDu-U_Y4/s800/20131220_193947.jpg

https://lh4.googleusercontent.com/-LWt7F2bC-Lo/UrTplr4VuzI/AAAAAAAAG2c/ALuVN5ki53s/s800/20131220_193959.jpg

All of the rear bolts have some slight distortion but are not stripped like the other one. When I first glanced at the other one I though LMT went to torx bits. You can also see the mold marking on the last one.

None of the gas keys are chrome lined -
https://lh3.googleusercontent.com/-GL11DogHdd0/UrTpmVIFJ4I/AAAAAAAAG28/lqWYPLiZadA/s800/20131220_194316.jpg

556Cliff

12-20-13, 20:07

Thanks for the pics.

I purchased an LMT Enhanced FA BCG around September 2011 and it had a very rough finish, it also had both gas key screws stripped out.

I had no confidence in the torque that may not have been applied to the stripped out gas key screws so I replaced the key and screws with a new set from Bravo Company.

I also sent that carrier off to get the NiB-X finish from WMD Guns, which did not block off the small vent hole to the rear of the three vertically aligned main vent holes.

bullseye

12-21-13, 08:04

I had one come in from LMT this week also, it is as yours. The rear gas key screw is a tad boogered up, the front one is not. Also no MIM ''dot on key, but it is black inside so I assume that it is MIM--- OK with me. I had ordered it about a month ago, so they appear to be getting back in stock a little quicker.

EzGoingKev

12-21-13, 15:49

I also sent that carrier off to get the NiB-X finish from WMD Guns, which did not block off the small vent hole to the rear of the three vertically aligned main vent holes.

Could you post some pics?

556Cliff

12-21-13, 16:52

Could you post some pics?

I wish I could, but unfortunately I don't have one of those fancy picture taking phones to be able to do any of that magic. :sad:

E-man930

12-21-13, 19:57

You know it would be nice if folks who own LMT enhanced bolts posted in the LMT enhanced bolt thread and folks who owned LMT enhanced carriers posted in the LMT enhanced carrier thread... I'm not bitching because I do appreciate the media but it gets a little confusing when people don't read before they post.

Mall_Ninja

12-22-13, 01:47

Might still be a MIM key, just with the mark somewhere not visible.

Or simply machined off…

None of the gas keys are chrome lined

Thats because LMT nitrocarburizes them, which is black and looks the same as a non-coated plain parkerized key (like a DPMS)

BufordTJustice

12-23-13, 09:11

Or simply machined off…

Thats because LMT nitrocarburizes them, which is black and looks the same as a non-coated plain parkerized key (like a DPMS)

A nitro'd/melonited gas key would actually be a good thing. I have never heard this before, though. Do you have a source for this info? I'm interested....

mtdawg169

12-23-13, 10:07

A nitro'd/melonited gas key would actually be a good thing. I have never heard this before, though. Do you have a source for this info? I'm interested....

They actually went to melonite a couple of years ago.

BufordTJustice

12-23-13, 10:55

They actually went to melonite a couple of years ago.

Roger. Good to know and thank you.

So I guess my gen4 carrier has that feature.

Goldorak

12-23-13, 10:56

"The only finding I discovered is that when I brought it home I disassembled the BCG to inspect the internals. I noticed the cam pin had quite a bit of wear for so few rounds through it. I reassembled the BCG without cleaning but I did add some more fireclean clp. "

I just remembered that the LMT cam pin broke in my gun (CMMG mid-length, LMT enhanced bolt and enhanced carrier) after an unknown number of rounds (a few thousands?). I discovered it when I took it apart for cleaning, so, no telling when exactly it happened.

mtdawg169

12-23-13, 11:07

Roger. Good to know and thank you.

So I guess my gen4 carrier has that feature.

No problem. Sorry for the short response, but I was in the car. I would think yours does have it. If you don't see chrome in the gas key, it should be melonited. I think they started doing it around the time they went to MIM keys.

Mall_Ninja

12-23-13, 12:47

I think they started doing it around the time they went to MIM keys.

Thats my understanding as well. Seems like cutting costs going to MIM allowed for the added cost of Meloniting. Seems like a good choice to me. Id rather have a Melonited MIM key than a standard chrome lined one...

EzGoingKev

12-23-13, 12:52

Thats my understanding as well. Seems like cutting costs going to MIM allowed for the added cost of Meloniting. Seems like a good choice to me. Id rather have a Melonited MIM key than a standard chrome lined one...
I really do not think it makes a difference as you do not see gas key failures. You do see gas key bolt failures though and I would rather see money spent on a high quality fastener.

Mall_Ninja

12-23-13, 13:06

I really do not think it makes a difference as you do not see gas key failures. You do see gas key bolt failures though and I would rather see money spent on a high quality fastener.

Agreed, if you mean "failures" as in "broken". In my opinion, the "wear" of the sides of the gas key in the upper and the erosion from the gas tube is where I think the Melonite is the better choice. It may even be preferable for the fasteners to be a bit soft rather than risk being too hard. Being able to spring and absorb energy rather than risk a fracture (yield) seems a better choice. Even if the Allen or Torx portion gets distorted a little, I still consider them to be a one time use fastener anyways. As long as they can later be removed its a non-issue. Even if they get distorted enough to not be removed easily later (not likely as the direction is opposite), thats an easy fix as well with an end mill or drill press...