I'm also in the process of doing three Form 1 builds from Solvent trap kits. Went to the Sheriff's Dept. today to get fingerprinted,but the person that does them is on vacation this week. On a Solvent trap,as long as the end cap isn't drilled,it can't be considered as a silencer/suppressor because you can't actually fire a live round through it. You do not need a Form 1 to purchase a Solvent Trap. However, Repurposing a solvent trap into an NFA controlled item prior to filing and obtaining an approval from the BATF is a Federal crime. You must have all your approvals from the BATF in hand before making any modifications. Nov 17, 2013 · I saw this 3d image of a Russian design in another thread and thought about using a modified version for a form 1 build. I was thinking of machining 5 M baffles from 4130 1.250 outside diameter bar stock, 60 degree truncated cones, with a 14mm length trunk, press fit and welded together in a stack, which is itself welded to the to the inside of the muzzle end cap. If you are reading this, then you might already know that some people convert their solvent traps into a DIY suppressor. Building your own suppressor is permissible so long as you have an approved Form 1 prior to making the needed changes. The ATF Form 1 submission process includes a $200 Tax Stamp and a Form 1 submission. I'm also in the process of doing three Form 1 builds from Solvent trap kits. Went to the Sheriff's Dept. today to get fingerprinted,but the person that does them is on vacation this week. On a Solvent trap,as long as the end cap isn't drilled,it can't be considered as a silencer/suppressor because you can't actually fire a live round through it.