Caution - Norwegian Krag barrels have a Left-Hand Thread!

Finally got my act together. Thanks to Bill Jacobs of Bolt and Barrel; how to modify a US Krag action wrench. Did not do it, but did get the clue about the cute little notch in the action  that was made for the wrench to fit in!  So I put a chunk of 7/8 steel stock in the mill, and together with a 1-1/2 " U bolt, which fits the exterior of the action just behind the handguard boss, came up with a nice wrench that works just fine. Turns out that the bottom of the notch is even with the center of the round part of the action. Hmmmm.

A couple of pix: all that's really necessary. The ubolt nuts should be snug, but should not be exuberantly tightened. Applying Kroil or the like for some days helped a lot. Good barrel wrench, and a dead blow hammer later, and off it came. Nowhere near as nasty as a 98 or a Swede.

Now: I solicit one more answer from you.  I have a nicely contoured 7 mm barrel, and contemplate putting a 7x57 Mauser on the action. I note the SAAMI pressures are equal for that and the 6.5x55. Any thoughts? I borescoped the original barrel, and it looks like the surface of the moon in there. Completely useless. As the pix I sent before (hope the new ones are a better size) show, the old bbl has been messed with, so collector value is low.
Unless someone can steer me to a NOS barrel ? (Joke).
Best, Don