First of all, I'm new to the forum and to reloading but have been shooting (not monster guns) for 25 years. I thought there was a .500" limit specified somwhere on the legality of new rifles. DISCLAIMER!!! All of this info was anecdotal to me so I'm asking 'cause I don't know. BUT... Big Sky Surplus in oregon has 20mm and 30mm vulcan barrels, brass, and projectiles available and... well... ya know...

http://www.sskindustries.com/14.htm

These guys are manufacuring a 14.5mm rifle out of the 50BMG round and have a destructive devices waiver This is REAL close in size to a Saboted Copper Slug out of a 12Ga. Except the SKS projectile weighs 2.5 times more and goes 2x as fast. Does anyone know the difference "in the eyes of the law"?

If this is a touchy subject let me know off line.

You can find all the nity grity at the atf web site. As I recall the code states that a bore diameter of not more than 1/2". This is not the groove diameter though so the .510" bullets are legal as long as the bore is .500"
the code further goes on to state that they can waive a round suitible for sporting purposes. You can request forms on the site somewhere, or get a number to call. They usually want everything in writeing.

I don't believe that the projectiles are considered a destructive device only if they are in loaded amunition.

Thanks, I actually called the local ATF guy here in Syracuse and was refered to the site with the CFR (Code of Federal Regulations) Sheeze wat a mess, our tax dollars at work.

I'll call him back when I'm serious about a monster gun.

Thanks again