Whether it's the superlative or the adams offerings, and 300 blk ambitions, it's a lot of tinkering to get a piston blackout AR to function with subs, and even with supersonic ammo. Handloading ammo helps, but thats a lot of labor also. Both Adams and Superlative discourage the use of their products in 300 Blk because they are tired of the phone calls to customer service. The gas port hole on the barrel you chose has to be opened up so large, like more than an 1/8 inch diameter for my 16 inch carbine, that many guys dont have have the expertise to do that at home (you dont need a drill press , btw ) I stopped at .141 (#28 drill bit... and you have to sneak up on it with the smaller drill bits first, assemble, go test fire it and start all over again). This is not for everyone. It took across a year and 7-10 trips to the range to proof out my setup. A year after I was done the SIG Rattler hit the market. Though expensive as the Rattler is, I figured I was half into a Rattler when I added up the cost of wasted ammo, gasoline, rejected parts, Number Drill Index, research time, , , , just get a Rattler and dont look back.
Superlative arms states clearly on their website NOT for 300 blackout.