Still issues w 300 BlkOut upper

krw

Sergeant
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Feb 28, 2004
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Arkansas
I posted other day about issues w 10.5” 300blkOut upper. Hav lots more details now. 10.5” with Pistol gas system. Mags run great on 223 uppers. Using 20rd Colts. Lubed BCG hard w Lucas. 10.3-11.0 gr 1680 w 208 Amax’s lded 2.230”. Shooting suppressed w SiCo Omega. 11.0gr is still subsonic and will lock bolt bak. Ejector seems weak? Seems to not eject the empty as hard or far as other uppers I hav. Hav not changed buffer or spring. Would like for it to shoot supers and subs both reliably. Any other ideas? Thanks
 

larryh128

Private
Minuteman
May 31, 2019
71
12
12
I'm not the expert on subs by any means but my thought is that you're not going to have cases flung very far with subs or at least the ones that I've shot. If they clear the gun, function, and the bolt locks open you should be good. Have you tried supers yet?
 

roostercogburn98

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Nov 3, 2010
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I never had any luck with 208Amax. I tried and they didn’t want to play right. I stick with 220g for my subs now and 147/150g for supers
 

Baron85

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Mar 18, 2012
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I’m running 208 amax with no issues on my 8” with can. There is a difference in injection between supers and subs atleast on my gun
 
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Docsherm

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May 6, 2019
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I posted other day about issues w 10.5” 300blkOut upper. Hav lots more details now. 10.5” with Pistol gas system. Mags run great on 223 uppers. Using 20rd Colts. Lubed BCG hard w Lucas. 10.3-11.0 gr 1680 w 208 Amax’s lded 2.230”. Shooting suppressed w SiCo Omega. 11.0gr is still subsonic and will lock bolt bak. Ejector seems weak? Seems to not eject the empty as hard or far as other uppers I hav. Hav not changed buffer or spring. Would like for it to shoot supers and subs both reliably. Any other ideas? Thanks

So what is the issue that you need fixed?
 

Docsherm

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May 6, 2019
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DFW Texas
I’m running 208 amax with no issues on my 8” with can. There is a difference in injection between supers and subs atleast on my gun

Same, i have a BA 8.3 Hanson barrel with an AAC SDN-6. I am also using an A5 buffer system with a Zero buffer. My go to SUB sonic round is the 208 AMAX. No issued with it cycling. It feels super slow when cycling but it works and it is quiet.

I will say that it must be lubed well or it gets all kinds of picky with Subs.
 

hlee

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Jul 14, 2012
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If the gun is firing a bullet down range and extracting and ejecting all of the brass and locking back on an empty mag, you don’t have a problem.