I've thought about doing the airgun smith thing, problem is in the area that interests me the most is suppressor, and that's a BIG grey area with the ATF. so right now I just tinker with my wn guns. I have a couple of modified M-Rods and a P-Rod that I modified to double the power for about 10 shots. makes a nice little carbine back yard gun.
I haven't verified it, but a co-worker of mine is into PCP air rifles. In a discussion with him, I was told they were legal for use on airguns, but had to be permanently affixed to the barrel (welded on or intergral to the barrel).
I'm not sure where he got the info from, but I'll ask him when I get back to work as that was one of the questions I had also.
I have an especially grey area. From my research, air guns are not considered firearms by the Fed, but it's unclear if a FFL is required to work on/manufacture them. From the ATF website: "Q: Does the ATF regulate the sale and possession of air guns? Is an air gun classified as a “firearm” under Federal law?
The term “firearm” is defined in the Gun Control Act of 1968, 18 U.S.C. Section 921(a)(3), to include “(A) any weapon (including a starter gun), which will, or is designed to or may readily be converted to expel a projectile by the action of an explosive; (B) the frame or receiver of any such weapon….” Based on Section 921(a)(3), air guns, because they use compressed air and not an explosive to expel a projectile, do not constitute firearms under Federal law — unless they are manufactured with the frames or receivers of an actual firearm. Accordingly, the domestic sale and possession of air guns is normally unregulated under the Federal firearms laws enforced by ATF."
To add to that, I'm a resident of Illinois which defines air guns under Public Act 097-0776 as follows.
"Firearm" means any device, by whatever name known, which is designed to expel a projectile or projectiles by the action of an explosion, expansion of gas or escape of gas; excluding, however:
(1) any pneumatic gun, spring gun, paint ball gun, or B-B gun which either expels a single globular projectile not exceeding .18 inch in diameter orand which has a maximum muzzle velocity of less than 700 feet per second or breakable paint balls containing washable marking colors;
(1.1) any pneumatic gun, spring gun, paint ball gun, or B-B gun which expels breakable paint balls.
So basically any airgun over 18 cal. with a muzzle velocity at or in excess of 700 fps is considered a firearm in Illinois and therefore requires an Illinois FOID (firearm owners ID card), at a minimum.