Should I Switch Bolt Carriers?

AR/M4 AR Technical Discussion
1

Hi,

I read here a lot, and yes, I’ve searched regarding what I’m going to ask about, and no, I haven’t found a definitive answer, yet.

I have a 14.5" mid-length. It’s less-than-top tier (CMMG), so I figure it’s probably over-gassed.

Before you say anything, I bought it before I knew better, and dumping it and buying something else isn’t an option.
I’ve already followed the advice in the old “Oh No! I bought a BM/RRA/Stag [CMMG]” sticky, and after 1,000 rounds or so it hasn’t had any problems.

Following the consensus here about 14.5" mid-lengths and buffers, I bought an H and H2 buffer to try.
I installed the H2 and it cycled fine, even rather dirty (after using my .22lr kit). I honestly couldn’t notice any difference in recoil.

So, I figure that it’s probably still over-gassed, even with the H2, and more reciprocating mass might be a good idea.

Of course I replaced the CMMG bolt with a BCM bolt right away, but I’m still using the semi-auto CMMG bolt carrier (yes, the carrier key is staked properly).

My question:

Should I replace the semi-auto carrier with a heavier auto carrier? The difference is less than an ounce (per weights posted by Robb Jenson), the cost is about $70.

Should I try an H3 buffer, too? This would add almost another ounce of reciprocating mass.

Or should I just do nothing and keep shooting it?

2

If it’s functioning fine and you are having no issues, there is no sense dumping more money into it. The act of trying to bring a hobby grade rifle up to spec can get expensive and eventually come to a point of diminishing returns.

I mean, how far does it go? Do you replace your 4140 barrel with a new 4150 11595E barrel? Do you replace your LPK?

Sure, the simple act of replacing a BC and Buffer is not that expensive or time consuming, but even after the fact, there will still be other issues in the back of your head.

So, in my opinion, since your rifle is functioning fine, you’re better off putting that money away and buying a high quality rifle some time in the future.

3

Well, obviously I’m not even considering replacing the barrel or LPK… My question is whether replacing the bolt carrier is past the point of diminishing returns or not.

Actually, this is the only issue in the back of my mind, and like you said, it’s easy and relatively cheap, and I like the idea of having the spare parts around, anyway.

I tried to make this clear from the start, but another AR is way down my list of priorities — this rifle is it for me for a long, long time.

On the other hand, every time I replace a part on this gun, that’s one part closer I am to a new rifle… I know, most people don’t start a new “build” with the bolt carrier group and buffer.

4

If you are willing to spend the money, you will slow down the dwell time on your most likely over gassed rifle for a little smoother shooting rifle. If you are not in the market for a new rifle, a quality M16 BCG and heavier buffer would be the best bet to add a bit more reliability and smoother operation of your rifle.

5

You could keep shooting it as is and order a spare BCG. Here’s one from PSA that’s reasonably priced

http://palmettostatearmory.com/1746.php

6

If it works why do you want to mess with it?

7

After reading your reply to my original response, here is my honest opinion. I understand if you don’t like what I have to say, so, respectfully, take it or leave it.

Given that you’ve made it clear that you will not be purchasing a new rifle:

If your goal is to go about improving reliability and overall performance, I believe you are going about it the wrong way. Here’s why.

Talk to the guys at ADCO about CMMG barrels. These guys see as wide a variety of barrels as anybody, and they believe CMMG to be the bottom of the bunch. The percentage of CMMG barrels that have a major problem is near 70%, according to them.

You’re about to spend $70 on a BC and possibly $40 on an H3 buffer (unless you have an extra already). For this price you are nearly halfway to buying a new quality barrel and FSB. There goes your problem of being overgassed, and now you have a high quality barrel to boot. You would no longer need to buy a new BC and buffer.

To me, that’s killing two birds with one stone. In this scenario, the juice is worth the squeeze. If it’s a money issue, I would just save up for a few more weeks and do it this way. Go for the root of the problem instead of treating the symptoms. I believe this to be a more sound long term decision.

8

I agree with a0cake. At this point just keep shooting it. You could try an H3 buffer and if it works better then just sell the others (recoup costs or keep as spares) and then just shoot it until it dies.

It’s never really cost effective to re-brand or rebuild something to spec because it will simply cost more.

9

Bimmer,
About your op, I would just shoot it unless you experience some real problem. The carrier and buffer weight would mostly effect extraction. Don’t over think it just go out and shoot.

10

I was in your position once, I had purchased a YHM fluted barrel because it was “cool” and later found out it was 4140 barrel steel and not the 4150 vanadium they advertised and because they falsely advertised I was able to get a full refund(very good on the part of YHM)and because I bought the barrel direct from YHM with shipping it was rather expensive for a nonspec barrel so with the refund I was able to get a Daniel Defense chf barrel;). Maybe you could sell the barrel you have and with the money you were going to dump into it you could obtain a quality barrel that you’ll be happy with for a long,long time.

11

Other than my suspicion that the gas port is too large, I’m pretty pleased with the barrel, and I don’t want to replace it.

Moreover, I don’t have the tools or skills to replace a barrel (maybe that’s lame, but at least I realize my limitations), and I’d need another muzzle device, so then I’m basically looking at a new upper, and that’s way more than double the cost of a new bolt carrier and buffer.

12

Don’t replace the barrel or the carrier. Carrier weight differences are negligible. I wouldn’t buy a semi carrier if I had the choice, but there’s no point in burning $70 for not much gain.

Those old cold unshrouded/ramped carriers can be worth replacing though…

13

Huh? Are you contradicting yourself here, or have I just not had enough coffee?

Or are you saying that I should NOT replace the carrier because of the weight issue, but I SHOULD replace the carrier because of other issues?

14

:smiley:

There are different “semi” carriers. Colt made a version that was ramped and forced the firing pin to cock the hammer ring cycling. That one is worth replacing.

A semi carrier with the shrouded firing pin isn’t worth replacing.

15

Aha. All clear now…

16

Really, a semi-auto carrier is one of those things that is really a non-issue that gets blown way out of proportion. Full auto is a bit “better”, but both work.

CMMG isn’t the best rifle- I wouldn’t put a suppressor on one due to the bores not always being centered. It really only becomes an issue if you are trying to build a super-accurate match-grade rifle or are trying to put a suppressor on since it can cause a baffle strike.

I’d just shoot it… most seem to work well enough. (I remember a few years ago they were the flavor of the month.) We sold a lot of their M4gery model and never had any complaints- some of our customers put some pretty hard use on them. They’re budget priced, but do well for the money you spend.

I had an issue personally with one of their products when production was cranking up and almost everyone (almost) was having some QC issues. They paid all the shipping, fixed the problem, and send me one of their immortal magazines for the trouble.

17

If you folks will forgive me my ignorance, I’d like to ask what the problem is that actually needs solving.

I see

I figure it’s probably over-gassed

I see

Following the consensus…I bought an H and H2 buffer to try

I see

I installed the H2 and it cycled fine, even rather dirty

What I don’t see is what actual problem is supposedly in need of ‘fixing’.

There’s no indication that it didn’t run right prior to fiddling buffers and OP states it ran fine after fiddling buffers.

No mention of ejection issues, recoil pulse issues, cycling problems or really anything that might cause one to want to look into things a bit deeper to see if there’s a solution.

If it is over gassed and works fine, it is over gassed and works fine.
If it is over gassed and as a result screwing up the way the thing works, then mabe start to chase the tail.

Otherwise all I’m really seeing is ‘I’m going to guess my stick is over gassed because of the manufacturers reputation and I’ve also heard others talk about changing buffers, carrier weights, and mabe even action springs, to perhaps help a consistently improper or poorly functioning rifle function properly and reliably’

Not even something as simple as a ‘trying to tone down a violent recoil for less muzzle climb/arthritic shoulder/petite female shooter’ problem AFA I can see :shrug:

18

What’s the problem? I still don’t understand.

19

That’s true. I have a beater Bushmaster 14.5 that’s over gassed. So what? I just shoot the shit out of it.

20

So you are telling me that you have a rifle that functions like it should. It feeds, goes bang, extracts and all that. I assume that it makes holes in paper some distance away…right? OK, now you dont quite like it because someone on an internet board said you don’t have the best in the world…is that about it? Stop reading bllshit and go out and shoot your rifle till it stops, then, either clean the crap out or replace the broke part. Replacing parts and components just beacuse someone on the net said your toy blows is a waste.