All, I have always been taught that the way to test the gas rings on a bolt is to stand it on its end after you reassemble it. If it collapses, it’s time for new rings. If not, you are good to go.
Is there another method? Am I wrong in thinking I need to replace them if they fail this test? I ask because the brand new BCG I have in a custom build failed this test after only about 500 rounds. The morning of the second day of Pat McNamara’s TAPS class I decided to clean the BCG and re-lube just to be safe. It failed the test that morning. I had an extra BCG with me, but decided to run the “bad” one until it died. It continued to run (though the 2nd day was mostly handgun).
I contacted the manufacturer and this was the response I got:
“I have never heard of the test you describe as being a reliable way to test gas rings. We purchase our bolts from a government contractor so I wouldn’t think they would be defective. We do not make them. We pressure test our carrier assemblies at 150 PSI before we ship them out. If you have access to an air compressor you could pressurize the gas key to see if it functions the bolt in the carrier. You will need one of the air guns that have the rubber end so it seals in the end of the gas key. As always make sure the ring gaps are not lined up. If you don’t have this equipment all I can say is shoot it with one round in the magazine. The bolt stop should hold the bolt open on the face of the bolt and not the bottom of the carrier. Hope this helps.”
I’m ordering new rings, but found it odd that they had not heard of this simple test, and that they perpetuate the myth that the rings need to be misaligned.
I wouldn’t think pressurized air would be an accurate test because the Bolt isn’t loaded up with coming out of battery under stress. I don’t have a doubt that you would not be able to move the Bolt out of the BC with Compressed air but what is that going to prove? It would probably blow the Bolt back without any Rings.
We all know the truth about lining the gaps up.
You might need to make sure the inside of the BC is properly finished where the Rings fit. A bad finish could prematurely wearing the Rings out.
Since you’ve already contacted the manufacturer, what make is the BCG?
[b]4. Check bolt assembly (5) for proper fit with bolt
cam pin removed. Turn key and bolt carrier
assembly (6) and suspend so the bolt assembly
is pointed down.
NOTE:
The bolt assembly must not drop out. If
weight of bolt assembly allows it to drop out
of key and bolt carrier assembly, replace bolt
rings (p 3-21).[/b]
The method you describe is taught by Ken Elmore and others and is also the accepted way. It’s the way I did it as well.
Any company that mentions the whole gas ring stagger shit is doing nothing but parroting an old idea and probably has ZERO understanding of the system.
yeah that compressed air test sounds hokey. I’d be willing to bet you could remove the rings and compressed air would still blow the bolt forward in the carrier… nowhere near the load the rings would see in actual operation.
First, that company is moronic… gas ring gap? People still believe that? And their air-pressure idea is just dumb.
Second, I have heard of the method you describe. It usually works alright, but is not the proper test. You’ll end up replacing the rings long before they need to be. Won’t hurt anything- you’re just replacing good parts.
Third, when performing the proper test (holding the bolt carrier so that the bolt has an opportunity to fall out), make sure it is dry. A well lubricated bolt will sometimes fall out when it otherwise would pass. The test is to be done dry.
Fourth, I have seen an M16 used by a local SWAT team fail the proper test miserably… practically no tension from the gas rings. I asked the officer that was accompanying the rifles during the rebuild if they had been experiencing failures with that rifle… he informed me that all of their M16s (I think they had 4 if I remember correctly) were functioning fine, and that one was no exception. So, just because a rifle fails the test doesn’t mean they won’t work… it just means you need to replace the rings because they are becoming likely to cause problems.
You can move the bolt with shop air into the carrier key. Not sure what it proves though. I think with no gas rings, most shop air, 40-60 PSI would still do it. You could reduce the pressure but then I think gas ring drag might jinx the test. I think the old tried and true methods are the way to go, even though yes, they do seem more like field expedients. If there’s any doubt, just spend the buck or buck-50 on new ones.
I myth-busted staggered gaps years ago with a video of my cutaway rifle. Lined them up and hand-cycled it 22 times. By then one had gone clockwise, one counter clockwise and one stood still. You can do the same shooting it-- line them up and shoot it. A) it will work and B) after a mag or less, when you take it apart they will be wherever the hell they felt like going!
Or, just run the rifle with only one gas ring… pretty well puts the myth to rest. In addition, the rings compress and seal off the gap for the most part.
Ned,
With a cutaway BCG, when the Bolt is inserted, can you see that the gap in the Rings closes?
Just seems like when the Bolt is pushed past the “shoulder” inside the BC, the Rings would compress because the ID is smaller.
Might be me misunderstanding but I always thought that little bit of resistance you feel when inserting the Bolt in the BC is the point where the Rings are forced into a smalled ID which closes their gaps.
Oh, certainly. That’s one of the pics in my class too-- using the cutaway. Just like piston rings in a car… when you measure “ring gap” for a car engine, it has to be with the rings in the cylinder. When the gas rings are where they do their stuff, the gap is closed considerably.
My new enhanced bolt will soon be on the market, it uses SIX gas rings and has little teeny weeny knock pins just like a car’s piston to make sure the gaps never line up :blink:
I use one piece rings (McFarlands) and never worry. And before anyone poo-poos their performance my 11.5" has over 7500 rounds through it with those rings and they are still going strong.
Gunz, I poo-poohed them until you told me you used them on the fleet. I figure if you say they’re good, they’re good.
If and when we conclude this thread, we ought to have one on how some guns seem to eat gas rings. Have not experienced it myself but some guys assume bad rings, I think more likely rough carrier bores-- and if it’s rough, and chromed like it oughtta be, it’s gonna be a long time before it stops eating them. Any thoughts, experiences, scientific testing / surface finish readings guys?
While the gun never failed to operate correctly, the 3 sets of McFarland rings I used never made it past 1k rounds before failing the bolt/gravity test. Theyre still on bolts around here somewhere, but not in any of my guns since I havent had any issues with standard rings in a long time.
In my experience they worked fine. I finally cleaned my SBR last night and checked my rings last night and they were good.
I have not had any issues with any of the ones I have used and the ones we had in Iraq were good as well.
I agree that it stands to reason if the inside of the carrier is shoddy then it would accelerate the wear. The same goes for not keeping your weapon lubed.
Thanks all. The BCG is a hard chrome from Young’s. I don’t see anything inside that would prematurely cause the rings to fail. And it isn’t like the bolt collapses slowly or a little bit. It drops like a rock. I tried it again this morning after removing all lube. It still falls like there are no rings.
I guess the next test will be to see if the new rings wear out in another 500 rounds.
Could possibly be that inside the BCG is too large?
Do you have another Bolt you could try to see if you get the same results with the test? If another Bolt drops the same,…
…there aren’t too many things it can be, I’d guess it woud point to the BC:
