Gas Ring

AR/M4 AR Technical Discussion
1

My gun started to short stroke during a training class (fire and fail to chamber next round). At first I thought it was the mags so I swapped to Pmags and still had the same failure.

I then swapped out the Dennies BCG with a LMT and my gun ran perfectly, since I was in a class I didn’t care to inspect it and then I forgot about it for a while. I chalked up the short stroking to improper lubing and didn’t think to inspect the BCG since I had only put 1200-1500 rounds or so through the BCG.

Well I decided to take a look at it today and this is what I found

Broken Gas Ring

Worn Gas Rings: Notice how the top left one is starting to show signs of wear

We’re only talking 1500 rounds here so I was kind of surprised. Interestingly my friend said his Dennies BCG failed exactly the same way after 500 rounds and he swapped out the gas rings.

I’m going to buy new gas rings for my other Dennies BCG (I have 2), I have a feeling they are either bad batch or something else is going on.

My question for M4carbine is:

Is this the way gas rings fail? It looks like they are getting worn from the inside. Would bad gas rings cause this or is there something else I need to be looking at?

2

Failure after 1500 rounds is not normal, but not totally unheard of. Swapping the BCG was also a good troubleshooting move, as it helps rule out gas issues with the gas tube and front sight/gas block.

I would install a fresh set of gas rings and check the interior of the BC to ensure there are no obvious burs or rough spots. Also, ensure the gas key isn’t leaking - make sure the screws are properly torqued and staked in place.

3

I’ve had some trouble with premature gas ring failure lately. I switched to Colt rings and they feel more substantial than new brand X rings.

4

Gas rings failing in that short of time is not normal and are most likely cheap junk.

Upgrade to some mil-spec rings and you shouldn’t have to change them out for 5-7k.

C4

5

BCM was able to run a middy for 16k rounds before the bolt was swapped out. 1500 rounds is definately not normal

6

Get some McFarland rings and try them. They are all I use now.

7

Grant, I had a set do the same thing in about the same number of rounds. The bolt and rings are tier 1. What would some of the other causes be? I have since replaced with Mcfarland and have 1130 rounds with zero issues.

8

Hard to saw. Maybe poor heat treating?

C4

9

Thanks for the responses I will probably go out and buy some quality gas rings.

So when gas rings do wear, it starts to wear from the inner diameter and not the outer diameter?

10

Oh yeah…thats the gas rings with the funky slash cut / / ends Ive been complaining about for so long here and over on Weapon Evolution.I never got past 500 rounds with a set on test/inspection and had one set actually cause funtion issues as mentioned above.The material that the gas rings are made of is soft and easily deforms.
Caused me to move to using the McFarland rings as recommended at the time by Grant and Iraqgunz.No issues since.
So Im glad to see it was not just me seeing these crap gas rings.

ETA
Be aware that there are also some odd ball one piece McFarland type rings floating around as well.So buy from a reliable source…a good example would be Grant at G&R Tactical.I know for a fact his USGI gas rings and McFarland rings are good to go.

11

McFarland rings are the only way to go if you want a reliable weapon.

12

Iraqgunz beat me to it. :slight_smile: Go McFarland and you’ll never look back. It’s the best $3 you’ll ever spend.

13

I’ll do you a favor, OP:

McFarland Gas Rings

14

This could indicate that the inside of your BCG is out-of-spec causing asymmetrical and/or premature wear on your rings.