.50 BMG ammo is fired from a bore diameter of .500; thereby making it legal to own and or build. Not full auto though. Yes you can use military ammo.; it falls in the .500 bore rule.
The sporting provision for cartridges above .500 bore, means ammo like .577 Nitro, and the like. And shotguns.
But if you want to build something with a bore diameter over .500, that fires fixed ammunition, then you need that Form One, before you do anything.

So dose anyone know of other good places that sell or manufacture barrels?

quote:

Originally posted by dpcd:
.50 BMG ammo is fired from a bore diameter of .500; thereby making it legal to own and or build. Not full auto though. Yes you can use military ammo.; it falls in the .500 bore rule.
The sporting provision for cartridges above .500 bore, means ammo like .577 Nitro, and the like. And shotguns.
But if you want to build something with a bore diameter over .500, that fires fixed ammunition, then you need that Form One, before you do anything.

That includes buying a barrel? That's the only part I'd have trouble manufacturing. I want to secure a barrel before I start so I know what size I'm building.

I thought you said you didn't want to buy anything until you were sure you had approval to build it. So, yes, you can buy any barrel you want any time you want. Now, in fact. . Mate that with a breech before getting build approval, and you spend the next ten years in Leavenworth. Not at the Command and General Staff College there.

I may have said that. And I know someone who ended up there for a few months before shipping him to Quantico for his dishonorable discharge.... "all he did" was steal a pair of NVGs and had the entire squadron he stole them from locked down for a month and they missed the thanksgiving holiday too.

He got caught by telling something then pissed him off.

I understand what your getting at.

As I recall, destructive devices are more than bore diameter.

"greater than .50 bore"
"fixed ammunition"
"explosive projectile"

Avoid those and you are fine, but don't just take my word for it.

As for "bowling ball nortars" as short barreled black powder smooth bores.

I've never heard of anyone needing ATF paperwork for a replica civil war cannon...

Unless found a 30mm GAU barrel for $425. When making the breach am I going to want to use the crom-molly 4351(I think that's about the number). Will HAS bits be fine working that or will I need to bust out my ceramic bits?
I think I'm going to make this sucker a wildcat.

Now it's time to start talking with the anti freedom unconstitutional government monopolized threat of imprisonment and/or force agency better known as the ART.
Thank you everybody for your help and conversation.

Allan you are mostly correct; fixed ammo and over .500 bore diameter is a DD, with exceptions for sporting cartridges. Like .577 Nitro and the like. And shotguns. Does not have to be explosive projo.
James, you can mill chrome moly steel with standard tooling; standard gun steels are in the 4000 series. It isn't hard; It has to be heat treated for a breech block and breech ring. They do make 4140 pre hard, which will work, and it isn't all that hard either.