I read with interest about threading a post-ban barrel to add a compensator for use on a post ban lower.  My question is; Can I thread a post-ban barrel, screw a flash suppressor (Vortex) on it for use on a pre-ban lower?  

Forgive me if this has been discussed before.

Thank you.

Sure - pre-ban barrel and post-ban barrel are tossed about quite freely, but there's really no legal issue until a barrel/upper in pre-ban config is mounted to a post-ban lower.

You can take your "post-ban" barrel/upper and thread it, put on a flash hider and a grenade launcher, and weld on a bayonet lug quite legally.  But you couldn't then mount that upper on your post-ban lower.

Oh, I just reread your post - the sticking point is that you have to permanently cover the threads (blind pin and weld, usually) to use the barrel on your post-ban lower, which would preclude easily switching over to a vortex for use on your pre-ban lower.

If you really wanted to swap the muzzle devices, you'd need to go for a non-threaded attachment, like set screws or a tri-lock of some sort.

Circuits, Thanks for the information.  I kinda felt that would be the situation.  I picked up a Colt Gov. Carbine, A2 with the straw barrel, the other day and want to use my postban flat top on it.  I guess I'll have to buy a 20" bull barreled flat top for my postban gun.  A guy can't sell a gun let alone just "part" of one, right?  

And for me it's always the moral argument that wins. (I'm surprised my wife wasn't named Moral :) )

I'm thinking Postban good, Preban better.

Paul, would that be an all-terrain tread or a mud tread?[>:/]

You can have a postban rifle with a threaded barrel so you can use removeable muzzle brakes but the thread pattern must be a non standard pattern for which no flash suppressor is made. I have a postban rifle set up this way and I went through the trouble of getting a letter from the BATF assuring this was legal.
They basically said that non standard threads were ok as long as no flash hiders were made for that thread pattern but if a flash suppressor becomes available for that thread pattern then the threads would have to be permanently covered or removed.