This is .300 Blackout using new Federal brass with a Maker 200gr solid copper rapid expanding (REX) bullet from Idaho Ordinance Factory.
We tested 20 rounds from a 16" PSA 1:8 nitrided barrel with pistol length gas. It was soft shooting and consistent on steel targets at 200yds with a 10-15mph crosswind.
1st string of 10: avg 1057, max 1072, min 1040, stdev 10.8, spread 32 [cold barrel]
2nd string of 7: avg 1068, max 1085, min 1043, stdev 10.3, spread 42 [hot barrel]
(our second string of 10 had three chrono errors)
IOF loads for a chrono target of 1,050fps.
MOQ 40rds (two boxes)