^ Yeah, and that's the thing about "obsolete" ammunition as it pertains to antiques or replicas: it can go either way.
The three centerfire cartridges I know of that are "obsolete" are the .577 Snider, .450/.577 Martini-Henry, and the .50-90 Sharps. .577 Snider however, is pretty easy to make as it requires 24 gauge primed hulls, a .590 or .600 round ball, and some black powder. All you have to do is cut the hulls down a bit, measure the powder, and stuff the ball into it. Then you've got a working cartridge that can be shot in an old Snider.
I guess because all those components are sold separately, the ATF lets it slide, but God forbid if the hulls, powder, and balls were sold in a kit along with a boxcutter. The devastation that might cause would be akin to giving ISIS a nuke.
Then you could look at the Webley revolvers and .455 Webley. I'd be bold and say that the .455 Webley is antique because I can't find it in any gun store I walk into nor can I find it in an internet search. There may be some boxes of .455 ammo sitting around somebody's basement and are sold at a gun show, but I hardly call what a guy has had in his basement for 50 years an ordinary channel.
But, if Fiocchi decides to crank out some .455 ammo again for a limited run and it starts popping up online, it changes things.
I guess this is why the BATFE doesn't have a master list.
I don't mean to go on a rant here, but this goes back to creating a system to "keep guns out of dangerous people's hands" hence the ambiguity. I severely doubt some arms trafficker is gonna consult the BATFE website on a master list of antique guns and ammo so he can go to a gun show in Indiana and buy them by the truckload along with guns bought in a private sale and put them in a mythical van and drive back to Chicago to sell on the streets.
It's a system designed to control law abiding people because that's the only people the government and the law controls; the law doesn't control criminals. Even with all the restrictions and regulations on gun sales today, criminals are still getting their hands on them.
If somebody couldn't pass a NICS check and winds up with a Webley or a .46 Rimfire 1858 conversion and working ammo, what does it matter? Until a criminal act is committed with those guns, I don't see any reason it needs to be an issue. It's the same old concept of "it's not the gun, it's the person" that the anti's and the politicians can't comprehend.
)