New on the forum: am considering re-barreling an original pre-64 short magnum ( .300 WM, .338 Mag, etc) action to .375 Ruger cartridge. How much action work to get feeding reliably? Same question using a standard pre-64 action with 06'bolt face to 9.3x62? thank you for your help.

The 06 to 9.3 should be no issue. I have never fooled with a pre 64 I 375 Ruger so no clue.

375 Ruger case head is .532 OD; same as our belted mags, but no belt. So you have to do much the same mods as with a belted mag. OAL is the same as a 300 Win Mag, but the Rugers are a bit fatter, so little alteration, realize that the pre 64s have the feed rails machined into the receiver, whereas post 64 ones use the mag box to do the feeding. Harder to explain than do.
9.3x62 uses standard 8mm/30-06 actions and no alterations
are needed.

thanks for your replies. Mr. dpcd: so are you saying that the only mod. for the .375 would be feed rails? I haven't checked the comparative dimensions in feed rails between the action that I have to use (from a .300 Win. Mag originally) to say a .338. The recoil lug on this particular action is stamped .458 as were many of those short magnum actions, however I can't remember if each short mag. caliber had a different feed ramp dimension. thank you.

Forgot to say welcome. Besides calling dpcd "Mr" will give him a big head.

I bet a the ramps would be the same for the 300 &338 Since the 300wmag didn't come out until 1963 your action was probably not a 300 from the factory.

You used rails and ramp. Just to make sure they are two different items.

actually, it is an original .300 Win. Mag with a shot out barrel. Ya, I did use both words (rails and ramp) : actually meant the rails, but I suppose the same question applies to the ramp. I have read of both FN commercial and pre-64 actions used for the .375 cartridge but have never heard of what actually had to be done to them for reliable feeding.

Have to widen the front of the rails to accommodate the 375 bullet instead of the 30 cal one.
Yeah, dpcd is the logo marked on all WW2 Dodge truck bolt heads, and was used on many parts until the 1970s.
Dodge, Plymouth, Chrysler, and DeSoto.

quote:

actually, it is an original .300 Win. Mag with a shot out barrel.

I stand corrected. Glad I didn't bet a on that one.

Get some 375 ruger dummy rounds and see how they fit in the mag. They are big and the mag box isn't designed to hold a round of that dimension.
Edit found a pic:
The pre 64 mag box is more square with less forward taper than the modern winchester so it might work

great picture mr. dead-eye ! Looks promising. I'll have to find some rounds to try. thanks much.

I built (and sold) a 375 Ruger built of a M70 Classic. Used a 300 Win Mag action as the basis for the build. Feeding from the magazine was never a problem. Loading the the magazine with 2 down, and one in the chamber was no problem. 3 down just didn't happen until I got one of Duane Weibe's magazine boxes and follower. Then all was well. Duane's mag box requires a bit of inletting in a factory stock and even some of the aftermarkets. Not a bog deal though.