So,
I was able to take the kit out on 9/2. I bought two barrel's, one for me, one for a friend who also has a UZI/Bowers can.
In one pack, the barrel locking nut was warped. The other nut was fine. (Because of the threading for the Mac can, the stock locking nut will not fit, you need a nut with a larger center hole)
One barrel would fit in both guns (my friends and mine) BUT, one barrel WOULDN'T fit in his. Off, just by a tiny amount.
So, we setup one UZI and got out to take it for a ride. It fires part of a magazine fine. GREAT comes the yells. Then, sadness. The rest of the magazine was getting light primer strikes. Working with JLM and it appears that the barrel is a smidge to long. (under .01 inch) Just enough that it stops the bolt before activating the primer. Other possibility was that there was a burr of some sort in the chamber that didn't allow the round to load cleanly, thereby slowing the bolt and resulting in the same problem.
Ammo was fine, we ran through the remaining 1100 rds with the factory barrel.
I left the next day for a long vacation in England. Great trip, but I haven't been able to contact RPB concerning the barrel. I will tomorrow.
I'll let you know the results good/bad/other.
Eric