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Discussion Starter #1
66621

Should I be concerned about these swipes?

These were shot from a 2009 vintage ARP 14.5" SAM-R, 11 twist, 4 groove with an AAC SPR/M4 Suppressor with the following reloads:

New resized SSA 2009 vintage brass
29.0 grains H322
Federal small rifle primers (don't have any CCI 41's)
Nosler 110 grain Accubonds
2.292" OAL

Grouped 1 MOA at 100 yards for these 5 shots.

Weapon is functioning fine, but brass is being ejected at 2:00. Should I try to tune this?

I am about to mount a thermal scope and turn this weapon into my primary predator/hog night weapon and want to dial in my reloads first.
 

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Forgot to include that these 5 shots averaged 2430 fps with an extreme spread of 23 fps, 35 degrees F. Only one of the brass had a small dent in the side. All have a very slight rough feel at the edge of the base at the location of the swipes.
 

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2 o’clock is pretty good for a suppressor. You could chamfer the ejector hole in the bolt to help with the ejector swipes.
 

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Or,
radius/dome the ejector as not to bastardize/burr the bolt's breech face.

Adjust the gas block or install a heavier buffer to acquire a 4-4:30 ejection angle.
 

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The primers have nice rounded edges so these swipes are not from a high chamber pressure situation. Swipes seem to have some rotation associated with them indicating that the bolt is opening too soon which is common when running a suppressor without an adjustable gas block. I have to run my AGB turned down significantly and I have not had much success using heavier buffers/springs when over-gassed this much.
 

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My 12.5 brass looks exactly like this and ejects at 2 :00 since I had to install a 5" buffer and spring kit . Since I only have to use that tube for a couple of weeks a year I may not install an agb but I can attest to bolt timing can be rough on brass .




Sent from my moto g(7) play using Tapatalk
 

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Discussion Starter #8
66833

My old eyes weren't able to focus on the small Allen screw in the hole, so I took a picture with my phone and blew it up. I went through all the Allen wrenches I have in standard and metric, but couldn't find one to fit. Anyone know what size Allen wrench is needed?
 

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My AGB use 2mm. However, I would advise using some CLP, break-free, B-blaster, etc on it to help with the carbon build up. You may have to move the adjustment screw in and out to clean it every other trip to the range. CLP will be your friend. Reminds me I better check my adjustment screw and put some CLP on it.
 
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