I also have the 6 position A5 tube... but that is not the issue of course
What ammo are you using?
Is this a newer .070" gas port DD barrel or the older .080 port size? Like the poster above me, I'm curious which ammo you're shooting. I have a MK18 upper with the newer barrel and it prefers 5.56 ammo, especially in the cold.
NO Law.... The reason I am at such a loss is that I have built many rifles... never had an issue. The only thing I have done different is that I am using different manufacturers parts, as explained above, a green sprinco (Rifle length), and a mil-spec trigger. I am going to shoot the upper with another lower to see if it works. I will change the BCG... it is just guess work at this point.
Black River Tactical
BRT OPTIMUM Hammer Forged Chrome Lined Barrels - 11.5", 12.5", 14.5", 16"
BRT EZTUNE Preset Gas Tubes - PISTOL, CAR, MID, RIFLE
BRT Bolt Carrier Groups M4A1, M16 CHROME
BRT Covert Comps 5.56, 6X, 7.62
He also noted that was dimpled for MK12 gas block... would that be the issue? It has a BA gas block... doesn’t add up but...
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