Sorry if this has been beaten to death before, but my search didn't find a good answer...

I have a question about the legality of threading the barrel and installing a Vortex. The barrel is part of a "Millenial upper" I purchased from Fulton Armory. I didn't have a pre-ban receiver at the time, so I got the "post-ban type" upper with a bare muzzle (the barrel was made in the 1960s or 70s, so I guess you could call it a pre-ban barrel).

Is it legal to thread and install a Vortex in this case (of course, the upper will only be used on the pre-ban lower...)?

Thanks.

Sure thing - long as it only goes on pre-ban or fixed-mag lowers after you've threaded it and put the phantom on it.

it doesnt matter when the barrel was made since the barrel isnt the gun heck i could thread post 94 barrel's till the cows come home thats why i wonder why the hell Preban Uppers and Stocks sell so much. well it depends on where u buy em. just make sure its legal to put the barrel/upper is ok for the gun your putting on