Bolt Carrier Group Guide (and questions)

**clayart** · 29 May 2008, 15:33

what does "staked" and "shot peened" mean?

**TigerStripe** · 29 May 2008, 16:45

Staking is pressing a piece of metal into a screw that prevents the screw from becoming loose and being shaken or jarred out of place.

The portion surrounded by the square shows staking... very good staking.

Here is a good technical - scientific explanation of shot peening.

TS

**kjd2121** · 2 February 2009, 09:19

I would like to know how a BCG affects accuracy. I recently read an article that basically stated that the BCG had nothing to contribute to the accuracy. Hmmmm, probably many opinions on this. Are there real world test to confirm?

If I were to order the YM Match BCG vs the regular chromed YM BCG what would that get me in terms of accuracy?

I want to build a very accurate AR. Your help is appreciated.

Curious to hear the responses.

**Stickman** · 2 February 2009, 18:20

If you aren't handloading to very specific specs, I don't think you would ever see a difference. The bolt is either in battery, and locked up, or its not. When the bolt locks into the barrel extension, the carrier isn't doing much aside from waiting for gas to purge inside it and pull the bolt back out.

A poor carrier has its own set of problems, but thats another story in itself. High tolerances, and quality construction are important, but I would not expect much if any difference between group sizes by using different bolt carriers.

What sort of loads are you looking to shoot?

What distances?

What glass are you looking at using?

**John Hwang** · 4 February 2009, 20:24

Originally Posted by John Hwang

Just an FYI for clarification

The Young MFG BCGs DO NOT come staked from the factory. They use red locktite which have survived 10,000 round tests by Young. The staking was done at our shop as the additional insurance was beneficial.

I was corrected by a customer who spoke to Young and they are claiming that they haven't fired 10K rounds out of these carriers. So either I was given wrong information or I was mistaken.

**Arms_Reach** · 7 February 2009, 16:32

Hey Stick,
I read through the entire post and like what you are trying to do. It is nice to have a place with accurate data.

That being said, I bought a YM NM BCG in DEC. In your pics/description you list a blue insert in the bolt. Mine came from Young (not another vendor) without the insert, but with an "O" ring.

**Ryo** · 10 February 2009, 11:11

Here's a picture of a Y/M National Match BCG from Spike's Tactical. Apparently Y/M engraved the spider logo into the BCG for them. I had talked to Tom and if I remember correctly, he said that Y/M also staked it or them also.

Sorry for the poor quality picture..

**JustMatt** · 12 February 2009, 15:10

Whats the benefit to having a black oring instead of a black insert on the LMT bolt?

**TehLlama** · 12 February 2009, 16:08

The O-ring spreads the shock out over a wider area, theoretically longer O-ring life and longer service cycle where it helps with extraction.
Practically speaking, as the spring wears out, drop in a new one with a fresh o-ring, and you're set. Bolts themselves won't go through more than a couple such replacements (if that), depending on firing schedule, so any of the above will get the job done - chamber specs, buffer weight and spring longevity are more pressing issues usually, a 5-turn extractor spring in good shape will do lots better than a worn out 4-turn.

**JustMatt** · 12 February 2009, 17:29

Ok, so the O-ring acts just like the insert except it has a larger diameter. Gotcha, I wasn't sure if it was a LMT specific bolt thing or if I could do that to any bolt extractor.

**cebuboy** · 24 February 2009, 03:39

Long time lurker here, if I may ask, what advantages can be had from a Young Manufacturing M16 National Match Chromed BCG vs their standard M16 Chromed BCG?

Its half an ounce heavier and has more bearing surface, does that make it more reliable than the standard chromed BCG?

**Echo4Tango** · 14 June 2009, 01:46

Im with Cebuboy here, I think a great addition to this review would be to add a section that tells what these 'extra features' are, or more practically, what the manufacture's CLAIM it does. For example;

-The third gas venting hole is to increase reliability by lowering chamber pressures quicker than a standard BCG.

-The extra half ounce of weight is meant to slow down the cycle of operations to give the bullet more time to leave the barrel before parts start moving and there by increasing accuracy.

Obviously these are just guesses, but for the guys just getting into AR building or even the more experienced members out there that have just never had to deal with BCG's in depth before I think a section like this would help out a lot. Quite often the manufacturers themselves don’t tell you what their cool new innovations do, they just expect you to believe in them or trust that their product is better.

And I personally would also like to see a "Stick's Comments" section where you or the other Admin give your own personal experience with said product or feature because we all know that the manufacturer’s claim can often be vary far from real world performance.

The write up is great so far and now that I've just asked you to put 20 more hours into it Im going to shut up

**niner** · 22 July 2009, 10:45

What is the difference in an M16 and AR15 BCG? I know ARFCOM says, but that site is blocked at work, and for some reason this one isn't :)

**Stickman** · 22 July 2009, 22:07

The M16 carrrier is longer on the underneath, the AR15 version is shorter underneath, and will not trip the autosear.

**mlosi762** · 25 August 2009, 06:57

Can you run an m16 carrier in an ar15? Or does that pose potential problems?

Thread: Bolt Carrier Group Guide (and questions)

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