I'm in the process of putting together an AR and would like to get a threaded barrel so I can put on a flash supressor if/when the ban sunsets.  I have seen thread protectors that would make the barrel look post-ban(and have no flash hiding charateristics).  Would it be legal to buy a pre-ban barrel, chop off the bayo lug and put a thread protector on in anticipation of the ban expiring?  Or does having accessible threads alone make the barrel preban?

Thanks for any advice and sorry if this is a dumb question.  I only ask because I'm on the fence about what barrel to buy and would rather not have a barrel without a flash hider once the ban sunsets.  

Thanks again.

I'm pretty sure that just having threads capable of accepting a flash-hider is illegal. The only way the thread protector would work would be if you welded it on permanently.
But I'm not a lawyer so don't take my word for it.

Not legal at all.

most gunsmiths will thread, but then drill, pin and weld over the pin so it is permanent, but could be removed by said gunsmith if ban did sunset. I had this done on my AR with a muzzle brake. K2 did mine, looks very clean.

Nope, not legal on a post ban, but you can remove one of the pinned on brakes with a little work...Or get one of the designs that attatch W/ set screws for now..You can always get it threaded for an A2 later..