Many individuals have purchased thread adapters to permit the use of an oil filter as a “solvent trap”. The problem is that this adapter can also be used and is often intended to be used to create a suppressor. The resellers on ebay who sold these adapters have all seemed to have disappeared and many of their customers are reporting being contacted by local ATF agents to collect the parts they purchased.
Recently we have had several clients contact us about purchasing these “solvent trap parts” and using them to make a Suppressor with a Form 1. Apparently there is someone marketing these parts including baffles as a solvent trap to be used for gun cleaning. It would not surprise me, if ATF shut down the ability of companies to sell parts as cleaning kits or solvent traps and then began targeting the customers of these parts in much the same way as the ATF continues to contact the customers of the companies who previously sold them eBay.
ATF has taken the position, in the past, that a part to a suppressor is a suppressor and under this theory, if you purchase these parts, the parts may in and of themselves be considered suppressors. Paying the tax stamp on a Form 1 does give you the permission to manufacture a suppressor, but not necessary to purchase a suppressor manufactured by someone else. We would caution clients who are considering manufacturing their own suppressors from parts that ATF considers a suppressor as the purchase of these parts may require an approved Form 4.