This is as good a place as any I suppose for this. This has to do with maintenance and life expectancy of parts. Today I issued out 5 BM carbines (semi-auto) so we could qualify and vet a few local nationals. The carbines in questions haven’t see much hard use at all. They have been here longer than me, so I have no idea what the actual round count is.
All the weapons were clean and before I handed them out I did the basic check as well as checking the BCG and gas rings. Two of the five failed the gas ring check. These weapons were also used just a few weeks ago and I can only assume that they either didn’t shoot them or they malfunctioned and it was chalked up to “normal”. I replaced the rings and sent them on their way. Here is the odd part. After they fired them the weapons were brought back and I was told that 2 of them were malfunctioning (classical short stroking going on). I am totally scratching my head because I had just checked them. Sure enough I cleaned them again, check the gas rings and both failed. We are talking about less than 60 rounds being fired from the time they went out till when they came back.
So back to cleaning and maintenance. I think that this shows why it is smart to clean your stuff after shooting. At a minimum the BCG because there just is no way to tell when something is going to break or wear out. This could have been a fluke for sure, but I am keeping my eye closer on ths situation.
One test I learned about was to stand the bolt on its face with the carrier (clean) on a flat surface like a table and if the carrier slides down at all , the rings require replacement.
There are many pros here who may have another way to do this.
The other thing about gas rings is that they are NOT all created equal. On the cheaper brands, we typically find gas rings that need to be changed out after a few hundred rounds!
Had a batch of PM-spares from a certain bottomfeeder that included gas rings. I did a batch of guns, and they all failed the test within a couple of qualifications.
My gas ring test: I hold the BCG by the upright bolt. If the BC drops free from bolt, or nearly does, the rings get replaced. This method produces earlier failure than some others but there’s nothing wrong with higher standards.
Speaking theoretically, could a poorly machined bolt carrier be rougher on gas rings due to surface imperfections or tool marks on the interior surface of the carrier itself? This would (I would think) wear out gas rings more quickly than a carefully machined carrier, no matter the quality of the rings themselves.
I always check gas rings and usually using both the place the extended bolt and carrier(no guts) on the bolt and look for collapse and then I collapse the assembly and hold the bolt and see if the carrier slides under its own weight. I can only assume there are alot of variables in ring quality (not just manufacture, but by also batch) and carrier dimensons because I have relpaced rings at all sorts of intervals, but so far not less than 2k. I think it is a good idea to have several sets of rings around because they can go at any time.
Gas rings are funny.
I have had M4A1s that wouldn’t come close to passing the gas-ring test, but would chew through a grand of M855 over a week long course.
Seems to me that if all else in the system is working in harmony, the gas rings are much less of a concern.
I have also shot M4s with one and even two gas rings removed (standard CAR buffer and used but within limit action spring). Once again, if lubed and all else is right and fed good ammo (M855), no problem for at least 30 rounds.
This is not to say that gas rings are not important, just quirks of the system I guess.
If the bore of the carrier is machined rough the hard chrome will act like a file. The plating is actually quite a bit harder than the average file. Electro plated hard chrome plating builds rough spikes on any sharp edges like machining marks.
Things like hydraulic cylinders that are hard chrome plated are honed after plating to avoid chewing up the seals.
So…what would the procedure for replacing the gas rings be? As always a qualified gunsmith would be the best bet, but is it something that’s a pain to do? Or simple stupid that can be done by a serious shooter wanting to maintain his weapon? I put at any given month 100 rds through my AR. 2k since I’ve had her, Thanks for the great info. Very interesting.
I have found if you heavily lube the interior of the BCG and keep it lubed, the gas rings last phenomenally longer. I got 9K out of a set and they still passed when I replaced them.
BINGO!
Ive been complaining about this for months due to the exact same experience and is why I PM’d you about quality gas rings sometime back.
Some of the gas rings Ive got from a few of the manufacturers dont have the usual tear drop ends either,but rather a slash like cutout on the ends.Service life is extremely short on these by the way.Im talking a matter of a few mags.
I took your advice and installed the McFarland rings.No problems since.
Anyone with a little mechanical ability can replace gas rings.
Remove old gas rings. You can use needle nose pliers or a dentist pick to lift the ring and then force it out of the groove. Once you have removed all three clean up any debris in the channel.
Take your new McFarland ring and with a finger start one side of the coil into the channel. Once there hold it in place and then use another finger nail to feed the rest of the gas ring and it will essentially “peel” into place. That’s it. It takes about 45 seconds or so. YMMV.
