Yes, it can be legal to make a silencer. For everything Form-1, from silencer designs that are easily made, to filing forms with the BATF, to 3D modeling. Remember, you must have an approved BATF Form-1 to make a silencer. All NFA laws apply.
I had an interesting little project come along recently, a guy wanted a longer barrel on the Walther (needs to be over 4" here in NZ to shoot and this was 3 7/8"). So we thought we would make it more interesting by going longer but adding a thread for a can.
So first thing was to get the old barrel out which involved making a tool to jack the original out. I then made the new barrel and fitted it, complete with extractor groove and feed ramp. That proved ok and functioned just fine.
So next I made a K baffle can for it and in this case due to customer financial requirements went for just paint on the outside (I usually go full anodized). Anyway it turned out great and makes this little 32 acp comfortably hearing safe and a great little toy.
Of all the things I've lost it's my mind I miss the most
The only reason after 243 years the government now wants to disarm you is they intend to do something you would shoot them for!
http://www.silencertalk.com/forum/viewtopic.php?f=10&t=79895
The Stechkin is a personal favorite of mine. I have only seen one that included stock and suppressor. The velocity control porting is wonder of engineering, care to duplicate it along with the eccentric suppressor of modern construction. It would be a huge job that I doubt the client will pay for, but what a project.
The only reason after 243 years the government now wants to disarm you is they intend to do something you would shoot them for!
http://www.silencertalk.com/forum/viewtopic.php?f=10&t=79895
