Match Grade BCG, Necessary or Hype?

[boombatz]

Hey everyone,

First post here on the forum - Working on putting together my first Grendel and have started with an 18" Wilson Combat barrel. I'm hoping to see what kind of accuracy I can squeeze out of the rifle and am somewhat on the fence about a match grade BCG such as those from Young Manufacturing. I understand the premise being the tighter tolerances counter the non-distributed force from the gas key. I look to you experienced folks for feedback -

• Do you have experience using a match grade BCG and have you seen an improvement in accuracy?
• Would combining this with a billet upper further reduce "slop" and improve accuracy?

Thanks in advance everyone, very cool forum!

[grayfox]

I dunno, sounds like some kind of a marketing trick -- the term "match grade" just to bump up the price.
By the time the gas key comes into play the bullet has almost left the building...
Your bolt ought to be a good one -- like the monster one sold by BFT on here, or other good bolts.
But the biggest impact on accuracy is the barrel. Wilson does make a good one IIRC so you got that covered.
I personally like a NiB coated carrier but nitrided from a good company is also good, I stay away from parkerized simply to reduce friction.

[A5BLASTER]

Marketing hype.

Any ar15 bcg with the correct grendel bolt installed will work.

The bolt and bcg does nothing for accuracy, all the bolt does is hold the case and all the bcg does is carry the bolt and fireing pin.

[Mustangfreek]

[FRB6.5]

Be aware that tolerance stacking is a thing. I tried to use a Young NM carrier in an SPR build with a 5.56 LaRue 18" Stealth barrel (their bolt, gas and brake) and a BCM upper. Given BCM are made to the minimum internal dimensions and the Young carrier is oversized it wouldn't fully lock back when firing. While the gun did cycle and ejection was at 4 o'clock the bolt would hang on the follower after the last round.

I switched that build to a standard carrier and it worked fine. I moved the Young to a spare PSA upper I had parted out and made into another SPR with a White Oak Mk12 barrel. It worked perfectly there.

An interesting point is both uppers were AH marked Anchor Harvey forgings (new BCM now have their own forge mark though). The difference is clearly in the finish machining and tolerances.

If you watch the John Carlos videos on building/tuning match AR's the over sized carrier or adding set screws to change carrier tilt are more for tuning a specific gun that needs it Vs an item to start with.

For the typical home builder a BCM or Vltor upper is chosen because of the minimum tolerances and undersized opening for the barrel to hopefully allow for thermo-fitting instead of needing to shim. A home builder won't have the luxury of choosing from different sized barrel extensions and assembling their own barrel like a fully equipped gunsmith. This tight fit is usually the biggest return accuracy wise over a different carrier.

Properly aligning the gas tube with the carrier key of any BCG will be your best return for accuracy and wear in that area. A gas tube bender may be needed for final alignment. http://www.m-guns.com/tools.php

[boombatz]

Thank you for that feedback! I wish I had seen this last night, I purchased an Odinworks Billet upper, curious if it may have the same minimal internal dimensions when it comes to the barrel extension? I have seen videos on thermo fitting, seems as though an oversized extension needs to be chosen at barrel build time though so gas port lines up? - brings up another question which should maybe be a new post (not sure), - bedding with a compound or using shim stock?..

Thanks again for your reply

[Bigs28]

Im not sure about match grade but im a fan of the finish. I use cryptic coating mystic bronze bcg and bolt. I have zero lube in my gun and it cleans up super easy.

[Wethepeople]

Agree with what others have already stated. Haven't used Young NM carriers but used their standard full mass in combination with BCM upper and WOA SPR barrel.
When first assembled, while checking gas tube/carrier key fitment, which was fine, I noticed it was very tight going into lockup. Needed a little bump from FA. While properly charging the rifle there were no issues whatsoever so I had little concern and recognized the combination of small I.D. of the reciever and slightly larger O.D. and frictional surface area of the carrier was a little tight going into battery.
Some use and wear and this non-issue went away. Everyone of my friends who have shot the rifle out to 1000 yards are truly impressed with the accuracy of the rifle. I have been told by others not to change a thing on this rifle. Most accurate AR in the safe and competitive in FTR in good shooting conditions.

[FRB6.5]

Thank you for that feedback! I wish I had seen this last night, I purchased an Odinworks Billet upper, curious if it may have the same minimal internal dimensions when it comes to the barrel extension? I have seen videos on thermo fitting, seems as though an oversized extension needs to be chosen at barrel build time though so gas port lines up? - brings up another question which should maybe be a new post (not sure), - bedding with a compound or using shim stock?..

Thanks again for your reply

I've not used an Odinworks upper nor do I know anyone who has, so no idea how loose or tight they run.
In general using Loc-tite 600 series sleeve retainer is for when the gap is smaller than shim stock you may have available to you. A good article on how to measure and fit shims (and other accuracy tune up tips) is here:

https://www.ar15.com/forums/precision-rifles/Hellbender-s-a-k-a-Lostinthewoods-Guide-to-the-Ultimate-AR-fixed-/4-6919/?r=93708