AR10 Malfunction with Silencer

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Jackal

Jackal

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I have a DPMS GII .308. I have installed an SLR adjustable gas block and tuned it without the silencer. It cycles/functions great. I assumed it would be slightly overgassed with the silencer installed. Well, today I screwed the can on and it was short stroking.

Why/how can it short stroke with the can ON, when it feeds fine with it OFF? Is there a different malfunction that acts like a shortstroke that could be caused by the added backpressure with the silencer attached? Can over gassing act like short stroke? :confused::confused:
 
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I think yes after reading this. http://m.hornady.com/ammunition/superformance-in-gas-operated-firearms

Turn the gas down?

he gun is still in the process or firing while it’s trying to extract the cartridge case.

If the firearm and the ammunition are not in sync, there can be what is commonly identified as “pressure signs” on the cartridge case. This is exhibited by the movement/marring of the head of the cartridge case, cratered primers, flat primers, ripped or ruptured cartridge cases, “popped primers”, and/or any combination of these effects. If any of these “pressure signs” are apparent, stop firing immediately. If an adjustable gas system is installed, it is advisable to reduce the amount of gas flowing through the system by closing the gas port until the gun operates correctly.

With the installation of an adjustable gas system, gas pressure can be metered to a point that enough gas is applied to open the bolt, but at a slower rate to allow the cartridge case to return to its original diameter prior to the movement of the bolt, and thus allow for proper extraction.
Click to expand...
 
Probably overgassed to the degree that the BCG is moving too fast. Mag spring can't push the next cartridge up fast enough. Maybe a heavier buffer and spring will fix it.
 
I doubt it's short-stroking considering a silencer always increases gas pressure (with the exception of the unique OSS line of silencers). Is it leaving empties in the chamber, and are the case rims chewed up on those empties? That's not short-stroking, that's a sign of overgassing. The bolt is trying to extract the case too early before the chamber pressure has dropped. At that point the case is still expanded and sealed to the chamber walls, so the extractor often can't do its job and it skips over or tears the case rim and leaves the empty brass in the chamber.

A stronger extractor and a clean chamber can often help the problem, but the primary cause is overgassing.
 
I'll try dialing back the gas some more when the rain/wind lets up. The SLR gas block is only 6 clicks open from the full closed position.
 
Please describe just what kind of malfunction you're getting. If you're having the malfunction I think you are, it's the extractor spring
 
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