I work part-time at a local NAPA store. There is a NAPA 4003 filter in the backroom and is NOS. I can have the filter and was going to make a suppressor out of it until I started reading on the internetzzz. It appears you cannot use Form 1 with the ATF for fuel or catch cans to make your own suppressor anymore. The more I read the more I get confused. These laws are made to make you a felon. I can't see paying 299.00 for the same thing and having to wait a year on Form 4. Any of you guys used Form 1 lately?