Malfunction question

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Weetabix
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Malfunction question

Post by Weetabix » Fri Jun 26, 2020 3:07 pm

A buddy at work took his AR to the range. Brass cased Winchester fed fine.

Steel case Tulammo didn't. When he'd fire the rifle, the bolt would go home on an empty chamber. The trigger was set. When he charged it with the charging handle the round chambered fine.

I'm thinking the "texture" on the steel case was slowing the rounds in the magazine just enough that the bolt went over them rather than feeding, but I'm not sure. I've lent him a PMag to try to see if it makes a difference. A stronger mag spring in his mag might do it?

Does anyone know what was going on?
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Cobar
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Re: Malfunction question

Post by Cobar » Fri Jun 26, 2020 4:19 pm

Is the ammo shellaced? might make it hang up some.

I've heard Tula ammo can be inconsistant on velocity. Maybe it is so low powered that it isn't quite cycling the action?

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Weetabix
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Re: Malfunction question

Post by Weetabix » Fri Jun 26, 2020 4:44 pm

Maybe shellaced. He had a round at the office. It didn't feel smooth like normal brass does.

I wondered about cycling the action. I wasn't there, but he said it ejected fine and reset the trigger. I suppose it could be doing that without the bolt moving far enough back to pick up a round.
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Langenator
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Re: Malfunction question

Post by Langenator » Fri Jun 26, 2020 9:09 pm

It's probably, like you said, increased friction from the steel cased rounds slowing the upward movement of the cartridges enough that the bolt has already passed over the top of them when the next round gets into proper position. The BCG is moving a lot slower when the rifle is charged manually.

One way to test if it's a friction problem is to start with a full mag, and work your way through it, charging manually if it doesn't pick up the round properly. At some point, the friction from the remaining rounds should be low enough to allow the gun to cycle properly.

I don't know if a PMag or other polymer mag will lower friction on a full mag enough for it to feed reliably. What length gas system, what weight buffer, and what strength buffer spring is he running? Carbine length gas with a standard carbine buffer and spring will have the BCG moving faster than rifle length gas with a rifle buffer, or carbine/mid-length gas with an H2 or H3 buffer. If he's got a carbine length gas system, I'd recommend increasing the buffer weight (H2 or H3) to slow the BCG down.
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Weetabix
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Re: Malfunction question

Post by Weetabix » Fri Jun 26, 2020 9:34 pm

Langenator wrote:
Fri Jun 26, 2020 9:09 pm
What length gas system, what weight buffer, and what strength buffer spring is he running? Carbine length gas with a standard carbine buffer and spring will have the BCG moving faster than rifle length gas with a rifle buffer, or carbine/mid-length gas with an H2 or H3 buffer. If he's got a carbine length gas system, I'd recommend increasing the buffer weight (H2 or H3) to slow the BCG down.
Don't know the answers to those. I can't remember exactly what he has.

He said the last four rounds functioned properly, so I'm guessing friction is it, too.

I'll recommend trying heavier buffers and stronger mag springs. He bought a whole case of that ammo. 8-)
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Vonz90
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Re: Malfunction question

Post by Vonz90 » Fri Jun 26, 2020 11:53 pm

Weetabix wrote:
Fri Jun 26, 2020 9:34 pm
Langenator wrote:
Fri Jun 26, 2020 9:09 pm
What length gas system, what weight buffer, and what strength buffer spring is he running? Carbine length gas with a standard carbine buffer and spring will have the BCG moving faster than rifle length gas with a rifle buffer, or carbine/mid-length gas with an H2 or H3 buffer. If he's got a carbine length gas system, I'd recommend increasing the buffer weight (H2 or H3) to slow the BCG down.
Don't know the answers to those. I can't remember exactly what he has.

He said the last four rounds functioned properly, so I'm guessing friction is it, too.

I'll recommend trying heavier buffers and stronger mag springs. He bought a whole case of that ammo. 8-)
Shoot better ammo

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Weetabix
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Re: Malfunction question

Post by Weetabix » Mon Jun 29, 2020 1:19 pm

Vonz90 wrote:
Fri Jun 26, 2020 11:53 pm
Shoot better ammo
I kinda hinted at that... :D
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