Unfortunately yes. But there are ways around it.
check with the prosecutor's office
if a gun has a threaded barrel, (required for a silencer) it is classified as an "assault weapon" and is illegal in California.
yes silencers are illegal in montana
No, you have to have a tax stamp from the ATF... but with that stamp it is 100% legal.
Depending on who you are, no.
That is an extremely difficult question to answer with any accuracy, but the basic answer is, just like anything else that is illegal, somebody in the legislature doesn't think you should own one, so they passed a law saying you can't.
The local police can assist you.
Depends on who is using them and for what.
Silencers are illegal in SOME states for the general public, but only a few. See link below
JUSTICE BROWN
Yes, provided you have complied with the FEDERAL law regarding suppressors. This is governed by 18 PA.C.S.§ 908.
It depends on exactly what you're asking, but in every state in the U.S. you can go to jail for illegal possession of a handgun.