Most suppressosors are not user servsable by law. They must be made in a way that the end user can't get into them. And too do so would violate Fed law.
xring, if you have a link to the law that supports the three claims you made, please post it. No need to put a damper on things by claming there are more restrictions than actually exist.
I am making my own 22 caliber silencer for my P-22 and 10/22 rifle. There are no federal laws prohibiting servicing of a silencer. According to the ATF's FAQ a form 1 builder can not replace parts or make repairs that change the bore or lengthen the tube. There are no laws that prohibit opening up the silencer for cleaning or repairing parts. If I need to replace parts in the future, I have to either submit another form 1 (and another $200), obtain a license and class 2 SOT or send it to an SOT class 2 for repair.
Here are a few links; http://www.atf.gov/firearms/faq/ http://www.atf.gov/firearms/faq/nati...silencers.html
These links are no substitute for actually reading the law, but they are helpful.
You might want to check out http://www.silencertalk.com
. You need an email address other than a Gmail or Yahoo to register, but lurking there like I do can be very educational. I am sort of copying some of what I see there as some posters are kind enough to post drawings or photos of the baffles they use.
Edited to add; Subsonic ammo is not required when using a silencer. Subsonic bullets make less noise due to no sonic boom and can be much less noisy when less powder is used. Even subsonic bullets can make a humming sound when flying through the air, and they can be loud when impacting the target. I was rather impressed the first time I heard a suppressed ar-15 at the rifle range. It was not quiet like a suppressed 22 rim fire rifle, but the harsh noise was dampened very much.