I think they increased the diameter of the barrel simply to get more steel around the fatter RUM case.
Only problem is that as you said they kept the receiver the same so they had to thin the bolt locking nut thickness significantly which created other problems.
Be very careful not to overtighten these lock nuts on the RUM or any Savage for that matter. The RUMs have a bad habit of wanting to crack if overtightened. You can imagine the excitement that created with a round such as the RUMs with a barrel that is free wheeling!!!
This is the very reason why I fit a Savage barrel via the Rem 700 barrels when I work on them. Much less liability issues this way. Not as easy to change barrels but thats better then me paying some lawyors kids way through school!!
Thats my theory anyway.
They are both 26" barrels, new unfired sporter weights.
Allen Precision Shooting
Home of the Allen Magnum, Allen Xpress and Allen Tactical Wildcats and the Painkiller Muzzle brakes.
Kirby, That's my thought too. I guess some engineer wanted to make sure that the barrel shank in front of the action has a little extra safety margin. It certainly didn't make the action/barrel interface any stronger.
Sorry, but can't use them because I have the standard actions. The thought of turning them down to fit is tempting but I just feel that Savage probably knows something that I don't need to find out.
Thanks for the info anyways. My 7Mystic barrel is back and I hope to install it soon. Then a bit of stock work, fireforming and off we go with another project rifle to work up.