Crowboy, you should take a minute to investigate the other threads that have been hot lately.
Check these threads out first, and then come back to this thread:
www.ar15.com/forums/topic.html?id=104627www.ar15.com/forums/topic.html?id=103447www.ar15.com/forums/topic.html?id=101687www.ar15.com/forums/topic.html?id=101586There is an EXCELLENT chance that the ban will not be replaced. The reasons are clearly outlined in those threads.
To get your barrel threaded will require it to be removed and cut for threads on a lathe via a machine shop. The spec is 1/2", 28TPI, right hand. Length of threads is about .675 inches, measuring my Bushmaster barrel for reference.
Having a flash hider on hand for reference would be a good idea for when you have this done.
The bayonet lug is integral to the sight base. You will need to have a new sight base gunsmithed to the barrel which includes the lug.
It's not a part that you can just pull off and put another on and expect it to fit properly without fitting.
There is no law against owning a flash hider and a sight base if you own a rifle that is properly post-ban configured, but since they're cheap and readily available, and will continue to be so for many years to come, there is no reason to take any chance by having those parts on hand until after the ban goes away. Don't get those parts until then. Some people would say that having these parts with a post-ban barrel constitutes intent to perform the conversion, and I might agree...IF you had a barrel with the threads already on it and a sight base installed on it that already had the lug on it. I believe firmly that you could legally have these parts separate from your rifle if you didn't have a threaded barrel lying around.
CJ