so its finally time for me to start the process to get my first NFA item. I've decided on AAC's evolution 9. this will go on a sig 226. I need a threaded barrel. I want to do this as simply as possible (not really looking for/needing a bar-sto precision fit match barrel) and so all I really need is a drop in barrel. I assume this would work? http://www.topgunsupply.com/sig_p226-replacement-barrel-9mm-threaded.html I can pretty much drop that in, right? no machining or gun-smithing necessary? now, what about those threads. 13.5 X 1 LH. anything wrong with that? is there a thread thats preferred? the AAC makes available multiple threads with their suppressors, right? and I guess 13.5 X 1 LH would be one of them, since its a sig factory replacement barrel which i imagine is fairly common..? ok. refresh me on the whole tax stamp process. do I buy the suppressor first and then start filling out forms? where does one order the forms? I know there is edu somewhere here but I can't seem to find it. I'm sure I'll have more questions later.