Yep, legal. Legal to own and legal to build. I've built 3 of my own and helped with building 3 others. All 100% legal on Form1s. The current sharif where I live is so NFA friendly he actually has a rubber stamp made up for the ATF Forms.
Years ago when I lived in Kerr county I discovered (much to my horror) that Sharif Rusty did not "believe civilians should have those things". Not knowing about the trust rout at the time I had the Constible sign off. ATF said no, I sent a 118 page appeal (well the appeal was 2 pages the rest was supporting documentation on my arguments) and got my approved From 1 two weeks later.
There are ways to get it done if you really want to but be warned. Silencers are very addictive, you cannot stop at one.
PS. someone mentioned hunting in Texas. Current Texas Parks and Wildlife manuals state that suppressors are legal for all non-game animals and a valid hunting license is required. (must have the tax income youknow). You cannot use a silenced firearm on any game animal. I personally have shot axis deer with a suppressed .308. Talk about a hoot
