BCG fails gas ring test in only 1400 rounds.

I have a BCM 14.5” ELW midlength upper with their BCG and when cleaning today I did the gas ring test for preventative maintenance reasons. And when standing the BCG on the bolt face it doesn’t stand up to it’s own weight and slightly collapses in a little. Is this normal for a gun that has just under 1400 rounds through it? I haven’t had any malfunctions or anything like that at least.
 

Greg "Sully" Sullivan

Established
Vendor
VIP
What we teach in Armorer courses is that there are 4 gas seals in AR15 system:
Gas Rings
Bolt Carrier to Carrier Key (Gas Key) Fit (Good Staking is a MUST)
Gas Tube were it goes into the Carrier Key
Front Sight Base or Gas Block to Barrel Fit (This is a machining tolerance quality control thing)

The gas rings are a wearable part (Basically Disposable), as compared to the other seals. Think of the gas rings like tires on a vehicle, you only get so many miles on them. Gas rings are a 3500 round part minimum, anything after that you are on borrowed time, they will go a lot longer than 3500, so don't think you need to change them every 3500, so as long as they produce a good seal then use them. The moment they start to slip, if lives depend upon them, then consider the slipping a warning to get them replaced. In reality the gun will run for a while after they don't seal, but for how long, so if its a rifle that's a range gun only (paper shooter, fun gun, plinker), then run it until it doesn't run anymore due to the gun short stroking (Fail to eject or go back far enough to pick up the next live round off the top of the magazine), then replace them after the gun isn't running.

IMHO:
If Lives Depend Upon That Gun Running 100%, then Replace The Gas Rings Once They Start To Slip.

What wears them out is the carbon fouling that builds up inside the bolt carrier assembly and on the tail of the bolt, and as the bolt travels in/out of the bolt carrier during cycling, any carbon that the gas rings rubs across is an abrasive action and wears them out.

If you run a dirtier ammo that causes more carbon fouling, you will erode the gas rings quicker, as compared to a cleaner type ammunition that has less carbon fouling build up. This often times comes down to the gun powder that is being used, which means that if the ammo is loaded with ball powder, which is much dirtier, you will get more fouling build up, as compared to a stick powder that burns much cleaner.

The fouling build up then comes down to how people maintain their rifles. If they keep the heavy chunks of carbon fouling build up away by a good cleaning on a regular basis, then gas rings last longer. If a quality gun lube is used that breaks the carbon down and keeps it soft and somewhat liquefied (Think of how a good engine oil works inside an engine), then you will get less erosion as compared to using a lubricant that either burns up or grabs the carbon and doesn't break it down as well of which will result in more friction and less gas ring life. (In Armorer courses we show hands on examples where people used wheel bearing grease as a lube, and ground the bolt down in 2400rds). On top of that you have to consider that if people pull or push their bolt in/out of the bolt carrier, the gas rings will wear faster as they scrape them across a heavy and hard carbon build up as compared to a lube that kept the fouling broken down as much as possible and softer (kind of like a soot), hence the reason I like a good quality synthetic gun lube like Slip2000 "EWL" Extreme Weapons Lube.

So in simple terms, if you are starting to see wear at 1400rds, this is normal if they are starting to slip, and all the factors listed above contribute to it. Gas rings are a wearable item, and you will have to replace them on occasion.

I have several bolts that have seen upwards of 45K on them with the same gas rings that still have a seal. This is due to the factors of using a good lube that breaks the down and keeps it soft like a soot, doing regular maintenance to keep the heavy fouling from building up, and shooting quality ammunition that produces less fouling.


CY6
Greg Sullivan "Sully"
SLR15 Rifles
TheDefensiveEdge.com
(763) 712-0123
 
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Thank you for the very detailed reply. It was very helpful. I also emailed BCM and they sent me the instructions for the proper gas ring test.
 

Wake27

Regular Member
I had a Noveske that blew them out I think twice in about 2k rounds. I was using Militec which I thought was highly recommended but then saw indications that it actually was terrible for the gun and chalked it up to that.

Surprising, but at least they’re so small and cheap that it’s easy to keep spares.


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