I don't think any of the Mag 10 Roadblockers came from the factory w/ screw-in choke tubes. In 1984, I found a new-in-box Mag 10 and called Jess Briley on the feasiblility of threading the cylinder barrel. I sent Jess my new 22" vent-ribbed Roadblocker and he threaded the barrel and made me three choke tubes which he said was the first Roadblocker which he had done. The 22' vent-ribbed guns were only made in 1984-85 and cost an additional $34. The Mag 10's were discontinued in 1985. I bought my Roadblocker for $450 at a rural gun shop which had special ordered the gun for a customer who backed out and I got it for just over their cost.
