208 a-max with 5774 works +6db louder than 1680. although I do not have a load for such a long barrel, I do have loads for 16" 1:7 ABC micro 7..220smk as well as 240smk are my best suppressed loads. Shooting 57db-61db, 1040-1050fps 1 1/2"group@100yrds.. but the rounds are also my most expensive...