What's the point? What does this bolt give you that a new MP Colt bolt doesn't, other than being slightly easier to clean?
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What's the point? What does this bolt give you that a new MP Colt bolt doesn't, other than being slightly easier to clean?
There is no point. The standard bolt, with the addition of Crane's O-ring, works perfectly.
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
Some have had issues with the LMT enhanced BCGs in 10.5" uppers. They were designed for the 14.5" uppers, not the shorties.
I know what they look like, I have one. I just don't see what they offer over a MP Colt bolt.Quote:
Originally Posted by AR15barrels
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.
Sorry, I failed mind reading and did not know you had one. ;)Quote:
Originally Posted by generic
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.
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
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.
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.
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.
Thanks for the pics, I've never seen one before. It looks to be about as relevant as a forward assist to me, though.
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.
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.
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.
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?
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.
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.
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 ?
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.
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.
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 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.
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.
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 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?
Did you try contacting LMT and asking them about purchasing spares?