No, it's not even close. The Automag twistlock portion is only about 2 inches long, and the grooves are much thinner and deeper than the Tiberius grooves. There's also only 1 locking nub in a Mag, instead of 2 on the Tib.
If anything, I would think you'd want to use a barrel with the largest OD possible to give you the most meat to work with. You'll be turning it down to the proper size to get it to work with the Tiberius.