Came off a model 11 with a g preffix on the serial number. Savage chambered the ultra mags to recievers that had a larger thread diameter, some of these recievers had standard chambered barrels screwed on, thus the larger thread diameter. I believe small shanks are 1.055" and large are 1.115"
I would guess that the strikers are small shank. For this barrel to work you would have to turn down the threads on a lathe. Not a big deal if you have access to one.