You know, on those "pre-ban" AR's which were sold during the ban (because their manufacture date was pre-ban) used to have a barrel which was thicker but didn't do anything. I did not know this, and was pretty surprised to learn what was really going on. I'd go to a gun show and see all these AR's with the expanded barrel end. They would say it was a 16" barrel, but if you measured with a tape measure from the breech it would measure like 20". I kept seeing these, so one time I asked an FFL whom I knew at one of the shows what was going on with them. He explained that the last 4" of the barrel was not rifled, so the rifling only came out 16" from the breech face, and the last 4" was a larger diameter which the bullet just passed through. And that way they could say they were '16" barrels'. This made them legal during the ban. But wow, talk about a screwed up idea! And to think I almost bought one of those!
I'll bet there were a whole lot of folks who got one of those home and got a big surprise when they ran their first jag or brush down the barrel!!
I'll bet there were a whole lot of folks who got one of those home and got a big surprise when they ran their first jag or brush down the barrel!!