Since I have a new long range rifle (300 WSM) I'm thinking of re barreling my 7 mm Winchester Classic Model 70 into a big bore. How big can I go with a 7mm action? I know I can re chamber it up to 338 Win Mag but how big can I go without chopping the heck out of it? Is 375 H&H chambering too long for this action, any suggestions?
Thanks,
Sam

You can go to .470 Capstick or .470 AR on that action.

George

An M70 SHOULD have a magazine well long enough for the 3.6" class, like 375 H&H, 375 Wby, 400 H&H, 416 Rem Mag, 458 Lott and like GeorgeS suggested, the 470 Capstick. There is also the 465 H&H too, not sure if its on the .532 case head however. These cartridges should just be a barrel swap, maybe a tiny bit of feed work. Now, if you wanted to spend the extra money on modding the action to feed, you also have something you could build a 404 Jeff on, but it would take some feed rail work for sure.

Now of course, you can also do any of the 3.4" class rounds, like the 375 Ruger, 416 Ruger, 416 Taylor, 411 KDF, 425 Express, 458 Win Mag, OR any of the fine AR line of wildcats.

Thanks guys, initially the 375 Ruger caught my eye but I am worried about ammo availability so now I'm considering the 375 H&H.
Sam