I got my tax stamps back for my suppressors a few weeks ago and got caught with my pants down in regards to subsonic 300 blackout. I have a Hornady LnL progressive press and I’m using Lyman dies. Before I went started seating primers and dropping powders I made a couple “dummy” rounds with neither primers nor powder. I ran 5 pieces of factory 300 brass through the size by die, and it fell right into the case gauge. I seat 208 gr bullets to 2.25 and none of the dummy rounds pass the case gauge. In the spirit of full disclosure to this point I’ve mostly only reloaded 9mm, 10mm, and about 1200 .223. I know I’m a newb but my dies were taken apart and cleaned and I e played with my sizing die and different OAL and can’t get one to fall all the way into the case gauge.