Fixed barrels should not have any thing to do with it. I talking about the other end. Regarding the pressure in the suppressor when fired.
Just thinking if there is a spring at the end every thing could compress and and possibly cause less stress to the stainless baffles
.300 blackout and 223/556
Was thinking of using a engine valve spring, should also relieve pressure on the baffles by allowing some compression.
I could be wrong. Just thinking out side the box.
Thar information is correct however if you efile you don't have to send pictures you can take a selfie and upload it.
Atf claims 30 days from receipt of finger prints.
Mine was 28 days for 4 form 1 submissions.
Also you only need 2 finger print cards even if you are sending in multiple form 1s