Which Bolt Carrier?

[recon by fire]

I'm working on my first build. So far I've got a DPMS lower, BM LPK, Tapco T6 stock, and a 16" LMT upper. I will use it for target shooting, home defense, or what ever. I want to buy an LMT bolt and carrier, so I can atleast keep the whole upper LMT. I have experience with M4 and M16 rifles in the Army. So I am leaning towards getting a FA/M16 carrier from LMT. Just because I've used that type of carrier and I know it works. I'm just wondering, what's the difference between the SA and the FA? Which one is better? Which type do you prefer and why?

[markm]

The 16 carrier is slightly harder to clean in the firing pin collar area. But it's the CORRECT part to have.

I only run the emasculated carriers on the Colts that I have which were equiped with them from the factory. I can't imagine anyone recommending anything but the 16 carrier.

[Robb Jensen]

I prefer to use a M16 carrier. The AR family of rifles was designed around using that weight of a carrier. Semi carriers are a little lighter, they have the sear trip area milled off of them.

For M16 carriers I would recommend Colt, BCM, LMT, and FN contracted.

[C4IGrant]

M16.

C4

[Street Survival]

M 16 Colt or BCM

[AR-15A3]

I prefer and would recommend M16 bolt carriers with properly staked carrier key screws.

I use Colt and LMT M16 BCG and others like BCM and FN contracted are good also.

In addition to my LMT M16 BCG on my LMT 16" carbine upper I also upgaded my LMT standard carbine buffer with a LMT heavy buffer.

[TY44934]

As far as your listed uses, GotM4 answered the question.

RE carrier weight: there is a WIDE variety of weights that will "work."

1) At the extreme heavy end is the M16 carrier. Semi-auto shooters sometimes prefer this carrier based on the belief that its heavier weight carries more forward momentum to strip a round & lock in place even if there is some build up in the upper; this is why CMP/DCM competitors headed to Camp perry select this carrier. As Rob points out, this carrier best fits the original design for the AR platform. A good choice.

2) At the extreme light end, JP Rifles has managed to get a carrier made of 7075-T6 aluminum to function reliably in their rifles for competition only use. NOTE: How do you define "reliable"?? (try asking the military - they are STILL doing "reliability" studies more than 40 years after the AR was designed).

Steel carriers from reputable manufacturers (see GotM4's post) will meet the needs of 99% of users.

Regards,

Douglas

[markm]

RE carrier weight: there is a WIDE variety of weights that will "work."


And weight variances between carrier versions are minimal compared to weight variances in Buffer options.

GotM4 posted the exact weights before.

[Robb Jensen]

And weight variances between carrier versions are minimal compared to weight variances in Buffer options.

GotM4 posted the exact weights before.



Carrier weights:

JP stainless LMOS carrier 6.25oz
Colt non-shrouded 1/2 circle carrier 8.63oz
Colt shrouded 1/2 circle carrier 8.87oz
Bushmaster non-shrouded AR15 carrier 8.92oz
Bushmaster shrouded AR15 carrier 9.26oz
CMT M16 carrier 9.46oz
ARES G35 piston kit M16 carrier 10.54oz
Bushmaster gas piston AR15 carrier 10.10oz (w/screwed on solid carrier key).


Buffer weights:

CAR buffer 2.96oz
CMT H2 buffer 4.57oz
CMT H3 buffer 5.43oz
Enidine CAR buffer 4.34oz (newest type, softer spring rate)
Rifle length buffer 5.2oz
9mm steel buffer 5.6oz
Colt X buffer 7.9oz

I'll be measuring a low mass Young Mfg carrier probably today. I'm going back to a really light carrier buy don't know yet if I want a stainless Young Mfg or a stainless JP.

[TY44934]

Carrier weights:

JP stainless LMOS carrier 6.25oz
Colt non-shrouded 1/2 circle carrier 8.63oz
Colt shrouded 1/2 circle carrier 8.87oz
Bushmaster non-shrouded AR15 carrier 8.92oz
Bushmaster shrouded AR15 carrier 9.26oz
CMT M16 carrier 9.46oz
ARES G35 piston kit M16 carrier 10.54oz
Bushmaster gas piston AR15 carrier 10.10oz (w/screwed on solid carrier key).


Buffer weights:

CAR buffer 2.96oz
CMT H2 buffer 4.57oz
CMT H3 buffer 5.43oz
Enidine CAR buffer 4.34oz (newest type, softer spring rate)
Rifle length buffer 5.2oz
9mm steel buffer 5.6oz
Colt X buffer 7.9oz

I'll be measuring a low mass Young Mfg carrier probably today. I'm going back to a really light carrier buy don't know yet if I want a stainless Young Mfg or a stainless JP.

Robb - do you know the weight of aluminum JP LMOS carrier? I though it was a LOT less than the LMOS Stainless 6.25 Oz JP carrier - something on the order of 3 Oz., but it required special spring rates and a light , all-aluminum solid buffer to work properly. Also, I was also considering the Young's stainless competition carrier for use in 3gun (i.e. gunracing for fun); can you drop me a PM on that piece? D.

[Robb Jensen]

I don't know the weight of the aluminum JP carrier. The Young Mfg skeletonized one is 8.60oz, not really much (at all) lighter than my 1/2 circle unshrouded Colt carrier.

[taliv]

interesting weights. thanks for the info.


i'd love to see a sticky with weights of all the popular AR parts. It took a ton of research when I was building my lightweight (around four and a half pounds) into stocks, fore-ends, barrels, etc.

[Robb Jensen]

interesting weights. thanks for the info.


i'd love to see a sticky with weights of all the popular AR parts. It took a ton of research when I was building my lightweight (around four and a half pounds) into stocks, fore-ends, barrels, etc.

I think the Maryland AR15 Users group on Yahoo has a chart of different weights of stuff. If you need me to weigh something that you cannot other wise find just let me know.

[Kalash]

Not to hi-jack this thread........

but does anyone know where I could buy a Colt complete bolt and firing pin?

[Robb Jensen]

Not to hi-jack this thread........

but does anyone know where I could buy a Colt complete bolt and firing pin?

www.specializedarmament.com aka SAW (Ken Elmore).

[taliv]

thanks gotm4!

actually, the only piece of my lightweight build i didn't get a chance to weigh was the stock i purchased, which was the ace socom, but the ace website lists it as 16.5 oz. (the interesting thing here is that if i had gone with a standard M4 stock, which I believe to be 10.8 oz, the total weight of my AR15 would be 4 lb 4 oz including aimpoint and a pmag!)

i would return the favor, as i am using the aluminum JP LMOS carrier you're missing in the chart, but I don't have a scale to weigh it.

[Robb Jensen]

thanks gotm4!

actually, the only piece of my lightweight build i didn't get a chance to weigh was the stock i purchased, which was the ace socom, but the ace website lists it as 16.5 oz. (the interesting thing here is that if i had gone with a standard M4 stock, which I believe to be 10.8 oz, the total weight of my AR15 would be 4 lb 4 oz including aimpoint and a pmag!)

i would return the favor, as i am using the aluminum JP LMOS carrier you're missing in the chart, but I don't have a scale to weigh it.

Damn if you go with a T1 Aimpoint in a LaRue mount and a CTR stock w/o pad you could shave a little more weight too. The T1 w/LaRue is like 5oz.

I just found the aluminum JP carrier and it's 3.75oz but JP highly recommends their adjustable gas block and JP lighter hammer and spring. I use a full power gas block and Geissele trigger (which hammer hits harder than stock) so I'll likely go w/stainless LMOS JP. I figure it's a just little more than 2oz lighter but I can just run a Wolff XP extractor spring and a Crane O-ring and possibly Wolff XP mag springs in PMAGs and keep it running well.

Here's a list of stock weights I've measured:

CTR stock 7.56oz
CTR stock w/rubber pad 8.79oz
VLTOR stock non-clubfoot 7.76oz
VLTOR E-MOD 13.81oz
LMT M4 stock 6.80oz
LMT SOPMOD stock 11.05oz

[taliv]

yeah, that weight is with the micro T1 and larue. i have an adjustable gas block, but not the JP. I found a much lower-profile one. I went with the JP single stage trigger and light hammer too. I like the geissele, but i bought mine in early autumn before the single-stage geisseles were out (actually, i'm not sure they're out yet)

the LMOS carrier doesn't come with a bolt though, you know. the bolt I'm using is a standard MPI'd one with extractor upgrade. I consider the LMOS carrier a "wear part", but educate me if there's an issue with it and the extractor parts you mentioned.

[Robb Jensen]

If you start to have extraction problems like it leaving the empty in the chamber or releasing the empty too early which won't eject and or tries to feed a live round and an empty is still in the upper. If that happens upgrade to a Crane O-ring and/or a Wolff XP M4 extractor spring.

[skyugo]

what's the benefit of a super light carrier?
other than reducing overall gun weight i mean.
the AR is already one of the lightest rifles in it's class....

[taliv]

in theory, reduced recoil

[Robb Jensen]

what's the benefit of a super light carrier?
other than reducing overall gun weight i mean.
the AR is already one of the lightest rifles in it's class....

Less moving mass = less muzzle lift and felt recoil.

[skyugo]

Less moving mass = less muzzle lift and felt recoil.

ah i see. that energy has to go somewhere though...

[Robb Jensen]

ah i see. that energy has to go somewhere though...

This is why JP recommends the adjustable gas block........................that way you can adjust it so that it gets enough gas to run reliably but not so much that the carrier is beating the s*** out of the end of the receiver extension. I've found that using a lighter than M16 carrier and a muzzle brake/comp that the recoil move more linear, but the muzzle lift is less. This is the 'first step' down the path to the 'way', I think. ;)

[taliv]

also, just so we're clear, these parts are for games.

[Robb Jensen]

also, just so we're clear, these parts are for games.

Exactly. don't use these on a 'social' rifle. For 'social' rifles use a full weight carrier, like a LMT or BCM M16 carrier.

[5.56 JC]

Does having an M16 bolt carrier make that much of a difference in a semi auto?

I have been thinking about replacing my BCG in my Rock River but am not sure if just getting it properly staked would work just as good. I dont know but am starting to wonder if the MP testing on the bolt, barrel, ect pertains more to guys who run full auto guns as opposed to semi auto. Let me know if I am way off base.

[Robb Jensen]

Does having an M16 bolt carrier make that much of a difference in a semi auto?

I have been thinking about replacing my BCG in my Rock River but am not sure if just getting it properly staked would work just as good. I dont know but am starting to wonder if the MP testing on the bolt, barrel, ect pertains more to guys who run full auto guns as opposed to semi auto. Let me know if I am way off base.

I wouldn't just swap out a carrier if you're is presently working. I would stake it better and just get a H buffer to make up the difference in weight. I would get a BCM MP tested bolt to keep as a spare and the BCM SOPMOD upgrade kit for your current bolt. You should always have a spare bolt handy. Everyone should use MP tested bolts for semi and full auto guns.

[carbinero]

I've read bolt and barrels wear together, perhaps analogous to a chain and sprocket. If so, would it be wise to rotate after x,000 rounds so the back-up fits as well as the original?

[Robb Jensen]

I've read bolt and barrels wear together, perhaps analogous to a chain and sprocket. If so, would it be wise to rotate after x,000 rounds so the back-up fits as well as the original?

Just check each bolt with the USGI Field gauge every few thousand rounds as part of your PM schedule. As long as it won't close on that gauge you'll be fine.

[5.56 JC]

Not to hijack but I have a couple questions. What is the BCM SOPMOD upgrade and would using an h2 or h3 buffer work better than the regular h buffer. What about replacing the sping with an ISMI spring or the one La Rue sells any advantage there?

[Robb Jensen]

Not to hijack but I have a couple questions. What is the BCM SOPMOD upgrade and would using an h2 or h3 buffer work better than the regular h buffer. What about replacing the sping with an ISMI spring or the one La Rue sells any advantage there?

BCM SOPMOD bolt upgrade kit from www.bravocompanyusa.com

http://www.bravocompanyusa.com/v/vspfiles/photos/manufacturers/BCM.jpg
http://www.bravocompanyusa.com/v/vspfiles/photos/BCM%20Bolt%20Upgrade%20Kit-2T.jpg


You can use too heavy of a buffer so that why I recommend the H. If you'll be using an ISMI spring I recommend the standard buffer. Using the H and a ISMI or TacticalSprings.com buffer spring can cause short stroking if you're shooting .223 pressure ammo instead of 5.56 NATO pressure ammo.

[Aristogeiton]

I love this site and all of the great information:D

However, it never fails to make me worry about my ARs. :eek:

Now I'm worried that maybe...just maybe my 20" AR with a rifle gas systyem, A2 stock and a .2 oz lighter (lighter than the M16 bolt carrier) LMT semi BCG is battering my A2 tube too hard.

I'm crazy, I know.

I also know that I could add a stronger buffer spring or try to modify the buffer to add the .2 oz, but I'll probally just keep a close eye on the rifle and adjust it in the future if anything is wearing out.

Has anyone ever seen a buffer tube "wear" out? I've seen broken ones, but they were from hitting things etc. never worn out from shooting.

I don't use my ARs for real "social" work, but I like to think that if SHTF I have one of the most durable battle rifles possible.

Thanks again for all the great info!

[markm]

Now I'm worried that maybe...just maybe my 20" AR with a rifle gas systyem, A2 stock and a .2 oz lighter (lighter than the M16 bolt carrier) LMT semi BCG is battering my A2 tube too hard.

I'm crazy, I know.


Completely irrational worry.

My oldest AR is an A2 setup with the fully neutered half circle colt bolt carrier. Never a problem.

[Aristogeiton]

Thanks Demigod!

I feel better now:D

[TY44934]

Does having an M16 bolt carrier make that much of a difference in a semi auto?

. . .

I dont know but am starting to wonder if the MP testing on the bolt, barrel, ect pertains more to guys who run full auto guns as opposed to semi auto. Let me know if I am way off base.

Hi JC - you bring up 2 issues: Weight (16 carrier) and Quality (MP testing & shot peening).

1) MP testing & shot peening: I have seen many photos of broken AR bolts. Virtually all were in semi-auto guns.

In my estimation, a number of these failures were caused by putting many rounds of 5.56 mm NATO pressure ammo through an AR with a lower-quality bolt - particularly one with a harsh carbine-length gas system. MP testing is just that - testing. Its just QC. But, it rules out harline cracks from heat treating. Shot peening takes away the sharp edges where cracks can develope. The part is actually stronger and unlikely to crack after peening. These features are valuable in ANY AR, and I agree with GotM4? that you should use a quality MP/peened bolt like BCM or if you can find/afford one, a colt.

2) Weight: carrier weight in semi-auto is not really noticeable in slow fire. 99% of the AR-owning community only shoots thier ARs slow fire anyway, so you are correct: weight does not matter; the carrier you have is right one. A heavier carrier is also a reliable carrier.

Things speed up in many carbine classes or if you use your AR in "games" (as they are snidely referred to above). In that scenario, the extra carrier weight upsets the weapon and moves the dot off the target momentarily after every shot.

How long is the dot off target? - a fraction of a second.

But, on a 30 to 50 round string, those fractions add up. Timed excercises are just that - timed - and competitions are judged by time divided by accuracy. Both count. If your goal is to place aimed rounds on target as fast possible and the targets dont shoot back (ie reliability is not life or death) then there are benefits to a competition AR set up (including a lighter carrier).

My advice? Invest in a quality bolt with upgraded parts & don't worry about the carrier.

[5.56 JC]

Thanks for the replies guys it cleared up alot of my questions.

So this is my course of action. Get the carrier staked correctly, buy a MP tested bolt and replace the buffer spring with the La Rue tactical spring and leave the buffer the same?

P.S I mostly shoot lake city XM193 so I would like it if the gun recoiled less with the NATO ammo. Along those same lines I am thinking of getting a DNTC Compensator to help in this area as well.

[taliv]

(as they are snidely referred to above)

fwiw, my warning was not in any way meant to be disparaging toward games. I love games.

[TY44934]

fwiw, my warning was not in any way meant to be disparaging toward games. I love games.

Sorry, my bad. let the games begin! Its all good.