I loaded up a 6slr with a 105g amax at 2.79" and it feeds in my SA 700. It was originally just a factory 22-250. And I have a bit of room to spare.
Take a look at Roberts measurements and measure your mag, that'll tell you a lot.
As far as making the 6slr, easy! Use Whitley's dies and they turn out.
xdeano
http://6mmar.com/Super_LR.html
"With The 6mm Super LR/S Reamer:
For the 6mm Super LR/S Reamer above (i.e. with the .075" free bore, which has a shorter throating for across the course chambering, magazine feed rifles, varmint rifles shooting smaller or lighter bullets, etc.) the following bullet measurements were made to show at what OAL the noted bullets hit the lands:
DTAC 115's (Lot #204258) 2.842" OAL (A little back in case)
Berger 115 VLD (Lot #1422) 2.906" OAL (Good OAL)
JLK 115 VLD (No Lot #) 2.873" OAL (Ideal OAL)
Sierra 107 gr (Lot #0008747115518) 2.842" OAL (Ideal OAL)
Hornady 105 A-Max (Lot #2090321) 2.792" OAL (At jct of neck and shoulder)
Berger 108 gr BT (Lot #1539) 2.802" OAL (Good OAL)
Lapua 105 gr Scenar (Lot #LMLME1) 2.806" OAL (Ideal OAL)
Berger 105 gr VLD (Lot #1415) 2.887" OAL (Forward in neck a bit but works well)
Berger 100 gr BT (Lot #1945) 2.798" OAL (Forward in neck a little but works well)
Berger 80 gr Flat Base (Lot #800) 2.706" OAL (Good OAL)
Hornady 87 gr V-Max (Lot #2050099) 2.717" OAL (Good OAL)
Note: When the term "Ideal OAL" is used, it means the junction of the boat tail and bearing surface of the bullet is forward of the junction of the neck and shoulder of the case by about .025" or so. When the term "Forward in neck but good OAL" is used it means the junction of the boat tail and bearing surface of the bullet is forward of the junction of the neck and shoulder of the case by about .040" - .070" or so (depending on the bullet involved) which is still good because the cartridge neck is .322" which means you have about .250" plus of neck still holding onto the bullet. "Good OAL" means the bullet junction of the boat tail and bearing surface is still ahead of the neck and sholder of the case. "Back in case" means part of the bearing surface of the bullet is back beyond the necks/shoulder junction (although the bullets still shoot very well there in many cases)."