Failure to feed, please help.

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[ARCHIVED THREAD] - Failure to feed, please help.

Posted: 12/4/2005 3:22:32 AM EDT

I have a carbine with a Fulton Armory 11.5 barrel that was cut down from a 16 barrel.

It fires well until it begins to get hot. When it gets hot, it fails to feed and jams.

After clearing the weapon, and checking the round that failed to feed, I see that the bullet is inside the brass casing.

The bolt locks open after firing the weapon with a magazine and one round.

What seems to be the problem?

Thanks.

Posted: 12/4/2005 5:38:21 PM EDT

[#1]

sounds like low feeds possibly brought on by the heat acting on the rifle. What size is the gas port in the barrel?

Posted: 12/14/2005 2:35:29 PM EDT

[#2]

Gas port size is .078.

Should it be larger?

Thanks.

Posted: 12/14/2005 3:27:04 PM EDT

[#3]

check everything else first before fiddling with the gas port, you can't easily make them smaller, but that port ID is small for a 11.5" that size is used on 16", the bolt locking back means there is enough gas but it may turn marginal with heat and fouling.

check your feed ramps and check the gas system for leaks, start with the carrier key screws and the OD of the breech end of the gas tube v. the ID of the key.

have you got it hot THEN short stroke tested it?

what ammo are you using?

Posted: 12/14/2005 3:37:31 PM EDT

[#4]

Quoted:
After clearing the weapon, and checking the round that failed to feed, I see that the bullet is inside the brass casing.

Are you saying that the bullet has been pushed back into the case beyond it's normal seating depth?

Posted: 12/14/2005 4:23:02 PM EDT

[#5]

Quoted:

Are you saying that the bullet has been pushed back into the case beyond it's normal seating depth?

Yes.

Posted: 12/14/2005 4:29:18 PM EDT

[#6]

Quoted:

have you got it hot THEN short stroke tested it?

what ammo are you using?

Yes.

PMC, Sellier & Bellot and blue box Black Hills 75gr.

Posted: 12/14/2005 9:22:27 PM EDT

[#7]

are you holding the rifle as loosely as possible when you short stroke test it? try testing it one handed and see if it passes.

Posted: 12/18/2005 5:35:53 AM EDT

[#8]

Quoted:
are you holding the rifle as loosely as possible when you short stroke test it? try testing it one handed and see if it passes.

I did the test as told, with the weapon hot after firing about a hundred rounds in rapid fire.

With magazines with Magpul followers the bolt locks open.

With magazines with green followers the bolt doesn't opens.

I find that odd.

Thanks.

Posted: 12/18/2005 5:48:31 AM EDT

[#9]

short stroke test it without a magazine while pressing in on the bolt catch

[ARCHIVED THREAD] - Failure to feed, please help.

AR-15 » Troubleshooting

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