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View Full Version : Are CMT bolt carrier groups any good???


Trendkill
10-18-2008, 2:56 PM
Looking for a good BCG......I see that BCM are not to be found right now....unless anyone knows where to find them.

What about CMMG and CMT BCG's.....? Are they any good?? I hear the last batch of LMT BCG's might not be up to snuff....what should I get???

aplinker
10-18-2008, 4:53 PM
You can buy a stripped carrier and BCM bolt.

The biggest difference is BCM & LMT are HPT/MPI'd individually - and they don't cost much more.

Buy the LMT from a dealer who will stand by the product if you don't want to DIY, or wait on BCM.

PIRATE14
10-18-2008, 8:36 PM
CMT/LMT/ROCK RIVER/STAG......they are all good....

Have you guys figured out who makes BCMs yet....?

Ya know we routinely just take some rifles off the rack and blow through a 1000 rds on a rifle in a day and don't have any issues with bolts, carriers, gas keys.....etc.

I think that guys that have some issues w/ these items need to come up with round counts and type of ammo used, cleaning and lube methods......

Need some data points......

ChrisXD45T
10-18-2008, 8:40 PM
BCMs are in stock, I ordered one yesterday.

Trendkill
10-18-2008, 8:46 PM
Guess I will have to wait a bit....BCM says maybe at the end of October there BCG's will be ready to go. I gave them my e-mail address so that they could contact me as soon as they have em.

I want good stuff.....and I will just have to be patient. I try to get the best quality with all my firearms.....and this should be no different. This is so hard to be patient....but Im sure I will be happy I waited in the end. I haven't been this excited about a gun for a while.....I guess I have BRD real bad.

Trendkill
10-18-2008, 8:47 PM
BCMs are in stock, I ordered one yesterday.

From who??

ChrisXD45T
10-18-2008, 8:55 PM
From who??
BCM.

Sorry, I checked a minute ago and they are sold out again until the end of the month. I got my order in and have one on the way though, so, yay me. Sorry for misleading.

Trendkill
10-18-2008, 9:00 PM
BCM.

Sorry, I checked a minute ago and they are sold out again until the end of the month. I got my order in and have one on the way though, so, yay me. Sorry for misleading.

Yeah I could have sworn they were out......Damn you!!! Lol;)

ChrisXD45T
10-18-2008, 9:07 PM
Yeah I could have sworn they were out......Damn you!!! Lol;)
Yeah, I ordered yesterday - didn't think they'd sell out in less than a day, should have checked before I posted. I'll take pictures and tell everyone how wonderful it is when I get it, if that's any consolation.

Cliff C
10-18-2008, 11:11 PM
Yeah, I ordered yesterday - didn't think they'd sell out in less than a day...

Based on the time stamp of my "In stock" email notification (10/17 @ 16:11), my own subsequent successful order same day at 18:59 and noticing that BCM was once again OOS on the item just before 2300, it seems they sold out in less than 8 hours. :eek:

Ya gotta be fast. :)

Addax
10-19-2008, 2:07 AM
CMT/STAG Bolt Carriers Assemblies are totally fine.

I have one that I have used for full auto testing in our Gas Piston Uppers and I have not had any failures.

We use CMT, WOA (AA), CMMG and LMT Bolt Carrier Assemblies, and we plan on using Young Mfg. BCG's in some models of our upcoming Elite Series GPU's.

I belive BCM is using LMT parts, but I have not confirmed this.

aplinker
10-19-2008, 2:46 AM
CMT/STAG Bolt Carriers Assemblies are totally fine.


There's nothing wrong with them, but for $5 more you can get a properly staked key, bolt that's been individually MPI'd, shot peened and has a proper black extractor o-ring for carbines.



I have one that I have used for full auto testing in our Gas Piston Uppers and I have not had any failures.

Anecdotal evidence isn't any at all.

I once tossed a coin 8 times in a row and it came up heads every time. That doesn't mean the coin is fixed or that it will come up heads the next toss.

Shot peening enhances durability and MPI indicates whether an item is prone to failure, so it can be rejected. If a part doesn't undergo these processes doesn't mean it will fail, but that they're less likely to do so. You're buying insurance.

Also, what kind of system you run greatly affects this - for example, bolt failure is common with carbines, but dramatically less so with rifles.




I belive BCM is using LMT parts, but I have not confirmed this.

That's the rumor I heard, too. But it's all just rumor unless he confirms it himself.

There are a couple things different about BCM than LMT.

The earlier rumor was that they're CMT, but from their other lines of product.

Addax
10-20-2008, 12:23 AM
There's nothing wrong with them, but for $5 more you can get a properly staked key, bolt that's been individually MPI'd, shot peened and has a proper black extractor o-ring for carbines.

Anecdotal evidence isn't any at all.

I once tossed a coin 8 times in a row and it came up heads every time. That doesn't mean the coin is fixed or that it will come up heads the next toss.

Shot peening enhances durability and MPI indicates whether an item is prone to failure, so it can be rejected. If a part doesn't undergo these processes doesn't mean it will fail, but that they're less likely to do so. You're buying insurance.

Also, what kind of system you run greatly affects this - for example, bolt failure is common with carbines, but dramatically less so with rifles.



So many people on the forums toss up their personal experience (including you and I) with products we have all used, purchased, tested etc.

I am merely stating my experience with using a CMT Bolt (in response to the OP's question about CMT). I think shooting full auto is a good way to test the durability of parts.

I have also shot bolts we have procured from LMT, CMMG and WOA in full auto, and they are all fine, and we have not encountered any issues.

aplinker
10-20-2008, 1:32 AM
So many people on the forums toss up their personal experience (including you and I) with products we have all used, purchased, tested etc.

I am merely stating my experience with using a CMT Bolt (in response to the OP's question about CMT). I think shooting full auto is a good way to test the durability of parts.

I have also shot bolts we have procured from LMT, CMMG and WOA in full auto, and they are all fine, and we have not encountered any issues.

I wasn't really attacking, but durability is one case where you really can't use anecdotal evidence, especially with something that will be on a trend basis after some "mileage." The only way to test durability is with a number of samples until they fail.

I'm actually not saying CMT is bad; I'm saying there are others that are more likely to be better - for about the same price.

FreedomIsNotFree
10-20-2008, 2:06 AM
Ever consider a JP Rifles BCG? These are built for reliability and duty use. JP has a great reputation in the industry for quality.

http://www.jprifles.com/buy.php?item=JPBC-2

JP Full Mass Stainless Tactical Carrier with key installed.

Machined from 416 stainless steel for the utmost in reliability and longevity. Features dust cover notch and forward assist serrations. 100% increase in bearing surface for smoother operation, improved alignment and lower wear in the upper receiver. Recommended for Duty use where poor conditions demand the highest level of reliable function. Finished with a QPQ hardcoat process to yield incredibly hard and lubricious bearing surfaces.

Not for use in AR-10-type rifles.
Weight: 8.5oz with key installed

He's got em for $180 right now.

aplinker
10-20-2008, 2:20 AM
Ever consider a JP Rifles BCG? These are built for reliability and duty use. JP has a great reputation in the industry for quality.

http://www.jprifles.com/buy.php?item=JPBC-2



He's got em for $180 right now.

That means a complete BCG would run $235.

The bolt is really the critical component - it's subjected to the most stress.

Addax
10-20-2008, 10:32 AM
I wasn't really attacking, but durability is one case where you really can't use anecdotal evidence, especially with something that will be on a trend basis after some "mileage." The only way to test durability is with a number of samples until they fail.

I'm actually not saying CMT is bad; I'm saying there are others that are more likely to be better - for about the same price.

It's all good Plinker, I did not mean to sound defensive in my response, I was just clarifying my input and position.

Our mutual input does help those who have not had the exposure or experience with certain products.

I just checked my log book, and one of my test mule Carbine Gas Piston Uppers that I am using the CMT bolt in, has a 3120 rounds through it, and 1000 rounds of this were shot in FA.

I have another test mule Carbine Gas Piston Upper that has over 6800 rounds through it now, and this is using a LMT bolt.

No bolt issues so far in either of these uppers.

Of course, a better reflection of componenet high use and long term durability is a round count of 10,000+ and shooting in different conditions.

FreedomIsNotFree
10-20-2008, 1:32 PM
That means a complete BCG would run $235.

The bolt is really the critical component - it's subjected to the most stress.

Actually, if you went with a JP carrier and bolt it would be $245. Definitely not the least expensive option, but some are less concerned with price and more concerned with reliability/function.

We can debate the reliability/function argument, but if you haven't tested/used one, you really cant comment with any sort of authority.

Trendkill
10-20-2008, 9:05 PM
Thanks for the responses guys.....

Thanks Plinker for your input on the testing procedures.

Thanks Chris for the hands on info from the CMT BCG's.

I have a little time still to decide....no need to rush....I want to feel good about my purchase.

SJgunguy24
10-20-2008, 9:18 PM
I'm looking for a BCG myself. What would I expect to spend for a decent set up? I've seen them as low as 115$, i'm not sure what to look for.

J_Rock
10-20-2008, 11:16 PM
BCMs are NOT in fact repackaged LMT BCGs. I know of a place that has them in stock but you'll have to PM me for that. Ill reply after I buy my own ;)

Also I wouldnt run anything besides a solid carrier key machined with the bolt carrier on a op-rod piston gun. They have a nasty habit of shearing off the carrier key fasteners. Something I would consider if buying a BCG for a piston gun

aplinker
10-20-2008, 11:45 PM
I'm looking for a BCG myself. What would I expect to spend for a decent set up? I've seen them as low as 115$, i'm not sure what to look for.

Spend the extra $15 for a BCM or LMT, especially if you're running it in anything with a gas system shorter than rifle.

randy
10-21-2008, 6:24 AM
The JP stainless is lighter than the "stock" carrier I weighed it against. They also make a aluminum carrier that is really light. The aluminum carrier requires more lube, and does have a life. It's light and will help reduce recoil. A good trade off of between weight and reliability is the carrier that MSTN uses. Much lighter than stock and will last.