Bolt failures

**constructor** · 03-03-12, 16:30

Originally Posted by TangoSauce

I blew out the rings on my Bushy after a few thousand rounds. A friend of mine sheared his key off his Bushy. There's a moral to this story some where.

Needless to say, I will not make that mistake twice. Anybody want to buy a Bushmaster carbine upper? haha

Ask your buddy if the key broke from the front or if the rear of the key hit the lower receiver. It seems there are some short buffers that allow the key to contact the lower receiver.
If the bumper is made too short or gets pounded into the buffer body
the rear of the key can strike the lower.

**condition1** · 05-10-12, 13:06

Originally Posted by AR15barrels

Absolutely.
Those lovely angle-drilled MRP gas ports are done that way to reduce the effects of erosion over the usable life of the barrel.
Without the sharp edge of a typical 90 degree gas port, it's not going to START eroding nearly as quick.

Just for speculation, I wonder if someone could make a tool to fit inside the barrel to chamfer or countersink the inside of the gas port. Similar to a crowned barrel. The trouble would be making it small enough to fit inside the barrel.

**JoeBobJoe** · 10-22-21, 19:47

After only 400 Rd my newest bcg failed a gas ring test. The test I did is, (assembled bolt in open position face down on flat surface, & if weight of carrier by itself, can move bcg into closed position). Is this a valid test or a guide. BTW everything was running fine. I just never had a bcg fail this "test". Any knowledge on this will be appreciated.

**lysander** · 10-22-21, 21:54

Originally Posted by JoeBobJoe

After only 400 Rd my newest bcg failed a gas ring test. The test I did is, (assembled bolt in open position face down on flat surface, & if weight of carrier by itself, can move bcg into closed position). Is this a valid test or a guide. BTW everything was running fine. I just never had a bcg fail this "test". Any knowledge on this will be appreciated.

You're doing the test backward, the rings are bad if they do not support the weight of the bolt.

Place the carrier on the table bolt up and the bolt should not slide down unto the cavity.

**titsonritz** · 10-22-21, 22:32

Originally Posted by lysander

You're doing the test backward, the rings are bad if they do not support the weight of the bolt.

Place the carrier on the table bolt up and the bolt should not slide down unto the cavity.

I always thought they were suppose to support the carrier.

https://www.google.com/search?q=bolt...lqtsPsY-gsAU28

**AR15barrels** · 10-23-21, 02:06

Originally Posted by titsonritz

I always thought they were suppose to support the carrier.

https://www.google.com/search?q=bolt...lqtsPsY-gsAU28

The Army direct support manual says that the test is if the bolt falls out of the carrier with the firing pin and cam pin removed that the bolt carrier group needs repair.

Page 43 of this PDF file: http://ar15barrels.com/data/m16-m4support.pdf describes the Army bolt carrier bench test for ring tension.

Any carrier that will pass the "bolt face down on the table" test and hold the weight of the carrier will ABSOLUTELY pass the "remove the firing pin and cam pin" test that checks for the rings being completely worn out.

**JoeBobJoe** · 10-23-21, 13:54

Originally Posted by lysander

You're doing the test backward, the rings are bad if they do not support the weight of the bolt.

Place the carrier on the table bolt up and the bolt should not slide down unto the cavity.

Yeah, It can easily pass the test you described. It can't pass the test I did but rings feel snug. Thanks.

**JoeBobJoe** · 10-23-21, 14:03

I guess supporting the carrier is a test to make sure you gas rings are like new. Looks like the real test for bad rings is if your bold just falls under its own weight, no cam Pin or firing pin. It seemed the ring closest to the bolt tail was slightly worn. So I put 1 new ring on, now it passes the carrier weight test. Now I know it's easy to install gas rings, one more thing I don't have to wonder about.