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4/6/2014 8:20:04 PM EDT
Just got my SDN-6 Friday and got to use it on my sir today. Every case mouth had a flat spot after ejection. I could see where the cases were hitting the deflector on the upper so I taped a piece of cloth to it for padding. This stopped the problem, nice round case mouths. No other problems of any kind. Fed great, ejected to about 4 o'clock (after hitting deflector), and locked back after last shot every time. It did have a little more recoil than I expected shooting subs but this is my first sir and suppressor so i only have standard ar's to compare it to. Here's what I've got:

PSA upper and lower
Noveske 8.2" barrel
WMD NIB semi bcg
JP Enterprises captured recoil spring assembly
SDN-6 suppressor

Didn't shoot any without the suppressor but did shoot some supers with the suppressor. Did the same thing but not quite as bad. Cases were hitting farther out on the deflector and leaving a smaller mark.
Any ideas would be greatly appreciated.
4/7/2014 10:30:22 AM EDT
[#1]
I was getting the same thing until I put a Micro MOA Govnah adjustable gas block on my 12.5" SBR with a Liberty Torch QA can.

Nice controlled ejection, lands about 4 foot away, in a pile.
4/7/2014 10:39:44 AM EDT
[#2]
If it fires, extracts and feeds just fine, don't mess with it. If you mess with the gas system chances are youll make it undergassed and it wont fire unsuppressed.

Having marks on your brass is expected with a semi auto

The issues you are having are nature of the beast. If your worried about reloading the brass the dings at the mouth should come out with you size and then seat a bullet.

Non issue if you ask me
4/7/2014 1:14:47 PM EDT
[#3]
I'm not to worried about unsuppressed firing. It won't be shot unsuppressed much, if at all.

It is more than marks on the case mouth. About 1/4 of the case mouth is smashed flat. It's enough that the expander could very well crush the case during resizing. Haven't had a chance to try it yet. With supers the case hit the deflector farther back and only flattened about 1/8 of the mouth. These will probably resize but I won't be shooting them much.
4/7/2014 1:22:50 PM EDT
[#4]
Quote History
Quoted:
I'm not to worried about unsuppressed firing. It won't be shot unsuppressed much, if at all.

It is more than marks on the case mouth. About 1/4 of the case mouth is smashed flat. It's enough that the expander could very well crush the case during resizing. Haven't had a chance to try it yet. With supers the case hit the deflector farther back and only flattened about 1/8 of the mouth. These will probably resize but I won't be shooting them much.
View Quote


Heavier buffers then adjustable gas blocks is the route I would take then.

But it may not have enough gas to cycle the gun unsuppressed when going that route
4/7/2014 3:50:09 PM EDT
[#5]
300 blackout?
4/7/2014 6:43:22 PM EDT
[#6]
Yes, it is a blackout. Forgot that part.
4/7/2014 7:38:33 PM EDT
[#7]
I had the same problem with my blackout, heavy buffer reduced but didn't eliminate it. I have a 9" and a 16" both do it.
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