Got 8 of them off. The barrel nuts come off easy - just used a good quality allen key with a breaker bar. PB and MAPP before hand. I could get to two of the 13mm's with a standard box wrench. Both came out easily, but with their stud. One Barrel brought a stud out.
Got these coming tomorrow, hope they do the trick.
Astro Pneumatic 7412 1/4-Inch Drive Flex Socket Set, 6 Point - Metric, 12-Piece - Amazon.com