Issue with suppressed AR

[digitalshooter]

As posted on the other hide I was having an issue with a suppressed AR. I did as Padom instructed and closed the gas off to I think all the way and started opening up the gas block one click at a time. Thanks to that advice both my AR-15 and 308 AR are cycling reliably.

But still having an issue with the 308. Since adding the suppressor I might be getting light primer strikes. Sometimes when I pull the trigger I get an audible click instead of a boom. When I eject the round and look at the primer there is a small dent from the firing pin. I can usually load it again and it will fire the second time. One time it took three tries to get it to fire. This issue only appeared after adding the suppressor to the rifle. It has about 500 rounds through it before starting to use the suppressor. The BCG is going all the way forward.

I didn't get a chance to try it without the suppressor again but this issue never happened before so I'm sure everything is installed correctly. The specs on the rifle are:

JP 22" barrel with rifle length gas system
JP FMOS BCG
JP Silent Capture Spring W/O extra springs or weights
SLR Sentry 9 Adjustable Gas Block
Geissele High Speed DMR Trigger
Mega Arms Nickel Boron Receiver Set
175 grain Federal Gold Medal Match

 

[Boxcar]

Sounds like you need a stronger hammer spring. Suppressor issues would show up post ignition.

What ammo are you using?

 

[digitalshooter]

As stated in the first post it's 175 Grain Federal Gold Medal Match. It's about all I've ever used. Tried a box of a couple of other brands but they just weren't as precise as the Federal Gold Medal Match.

 

[NukeMMC]

Use pipe cleaner to ensure the firing pin hole in the bolt is clean. Same thing at the rear of the bolt carrier and bolt where the firing pin seats when the hammer hits it. These rifles sure carbon up with the cans on. Use the stiff bristle nylon brush and make sure the bolt face gets clean also.

 

[quicklx]

Try another trigger group with a stock hammer spring, and I would tear the BCG apart, clean and inspect everything. You may simply have a little piece of crap in the firing pin bore. Also make sure the BCG is well lubed. I had some weird stuff going on with mine when I first got it together and skimped on the lube more than I normally would and sure enough that was causing my issues.

 

[supercorndogs]

If your lube you put on your gas rings is too thick. When it migrates to the firing pin, it can slow it down and cause light strikes.

 

[JSTARSZ]

I just had this exact thing with a 308 AR with a Syrac Adjustable gas block. Basically the bolt would not close all the way forward and I would get light to no primer strikes - with a sickening click sound. I changed the spring back to a normal spring set-up and reset the Syrac like you are doing and it works well now. The spring and gas system was not strong enough to get the bolt back into battery.

 

[digitalshooter]

Thank you for the suggestions. I think it was the SCS was to light. I got a couple of tungsten weights installed yesterday to turn it into a H2 buffer system and took it shooting today. 30 rounds without a failure. The rifle was still dirty from the last two outings so I think I got it worked out. But I am going to clean it and start the reliability testing over and see how far it will go before a failure. So we will see.