Causes of broken gas rings?

[.40isthenew.45]

Not too long ago, I discovered a broken gas ring on my bolt. Ok, no big deal, probably just waited too long to replace them. Fast forward less than 1k rounds and, you guessed it, another broken gas ring.

They are cheap enough to just replace, but I can't help but wonder WHY? I don't want to be masking a larger problem and replace $5 worth of gas rings before whatever expensive issue that is breaking them rears it's ugly head.

There are no markings on the bolt or carrier to determine who manufactured it and nothing that I can see appears to be showing any wear. Gun doesn't show any signs of being over gassed, locking lugs look good, feeds reliably, locks back when it should, recoil not excessive etc etc....

Any thoughts?

[DenverGP]

I've seen a BCG that had an imperfection on the interior surface where the rings slide, that caused issues with the gas rings. I could feel a ridge using a plastic pick.

[Mazin]

I've seen a BCG that had an imperfection on the interior surface where the rings slide, that caused issues with the gas rings. I could feel a ridge using a plastic pick.

^This.
Next step would be checking the carrier for milling left overs.

[izzy]

I've never had these break nor have I ever replaced them. Is this a typical part that people replace every few thousand rounds? I've got rifles with well into the 20k (probably more) round count and have never replaced a single part on them.

[Mazin]

I've never had these break nor have I ever replaced them. Is this a typical part that people replace every few thousand rounds? I've got rifles with well into the 20k (probably more) round count and have never replaced a single part on them.

I also over the years have never replaced a set but I know guys that do it every 10-15k depending on how the rifle is acting or the amount of carbon build up that is in the Carrier.

[.40isthenew.45]

i just checked the bolt as I replaced the rings and didn't feel anything. The carrier looks good. The rifle runs well so I will probably just keep an eye on it and see what happens.

Thanks for all the input though. This is the only rifle I have ever "needed" to replace the gas rings on, and truth be told it was running fine, I just noticed the broken ring during cleaning and it made me curious.

[BPTactical]

Gas rings are a maintenance item, they will wear with use and lose tension. Next time you clean your rifle reassemble the bolt and carrier dry. Extend the bolt from the carrier and stand the carrier up vertically on the bolt face. The carrier should stay up, if it drops under its own weight the rings are worn/lost tension and should be replaced.
I have dealt with a couple of BCG's that when new would eat rings every range trip. After a couple thousand rounds they settled down and quit eating them.
My guess is they had either some tolerance or burr issues and needed a wearing in period.
Overgassed will generally not eat rings. Ejection should be at 3-4 o'clock ideally, if 12 to 3 it is overgassed and beyond 4ish undergassed.
I have seen huge differences in ring life using quality rings. Colt seems to wear best- I have seen DPMS & Toolcraft rings go to crap after 1 range session, broken rings are not uncommon.

[ChickNorris]

This ^^^

Ive had to replace them, twice. Check my bcg often specific to this & there is no obvious reason. 3rd set now & no issues, yet.

I shoot a lot though so it is possible.

[ray1970]

I change my gas rings, buffer spring, and ejector spring about every 5,000 rounds or so. Why? Because they?re cheap and by doing so I?ve never had any reliability issues with any of my rifles. Even back in the day when I felt like I was shooting quite a bit I was only changing these components every two or three years.

My only guess for ring breakage could be the ring groove is too wide and the rings are slamming back and forth excessively. I?d measure the width and depth of the ring groove and then compare those numbers to whatever the spec is and see if something is amiss.

[ray1970]

Oh. And my extractor spring. Forgot to mention that one.