I have a post 64 mod 70 in 300 WM which has never shot as well as I would like.

Thinking about maybe re-barreling to 375 h&h. Anyone have any experience with this conversion?

Regards,
hm

This can be done and I personally know folks that post here that will do it.....but I don't like doing surgery to actions like that and I find that it's actually less costly to simply trade the gun.....
Besides you didn't say you had a push feed....but if you trade you can get a CRF too.

Probably sound advice.

The rifle is a push feed and probably shoots fine for a hunting rifle (1.75 moa), so may be time to take it to a gun show and see what I can do.

Problem is have not seen too many 375's at local shows.

Regards,
hm

HM1996,

I asked the same question several months ago. It requires milling back and re-hardening the action, changing the ejector, magazine box, and of course rebarreling. The Gander Mountain folks wouldn't do it. I got a quote of around $2,300 from a smith who agreed to do it, but he was a "name" gunsmith. By comparison, rebarreling to a same-length action caliber would only be around $500. And buying a new .375 is $1000.

Steve

Thanks for the input, Steve.

That pretty well answers that question!

Regards,
hm

why does it have to be rehardened? they're conventional steel, easily machined.

i looked into taking one of the new controlled feed classic actions from 458 out to 375 and all i came up with it needed (other than barrel) was new extractor collar which has the stop that sets bolt throw length and a new magazine box and follower. $50 or $75 of parts at the time. the push feed models would have a different bolt stop arrangement and not sure what it'd entail. the magazine on all is the same outside but w/ spacers permanently installed to reduce length for the cartridge the rifle is chambered for (obviously not true for the short action m70's) so the bottom of the receiver is by definition already cut for the full length. a buddy has a push feed 300wby which is of course the full length and i don't recall anything radically different about it from the standard ctg models i've had.

If it trips your trigger you can have it rebarreled to .375 Taylor and that equals the performance of the .375 H&H and no changes to the action is required.....but now you have a wildcat.

Here's a better thought.....spend a "C" note and have the .300 mag glass bedded and barrel free floated and see if the accuracy improves.....I'll lay even odds you'll be shooting in the 1" range.....and won't want to trade.

Then watch the gun shows and pick up a good .375 H&H and now you have two guns!!!

quote:

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Originally posted by willmckee:
why does it have to be rehardened?

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You're correct.....The M-70 does not have to be rehardened.

got curious and looked in "the rifleman's rifle" by roger rule. quote: "...the pre-64 utilized three receiver types, the 'new style' had only ONE for all cartridges. this was 1/8" longer overall, designed for the longest chambered cartridge, the 375 H&H magnum, rather than the 30-06 as in the pre-64. ....The magazine well length for the 'new style' was 3.72" while 3.50" for the standard pre-64. (to gain H&H magnum capability, the well for the pre-64 was opened forward into the locking seat to 3.70")."

as i said, no action mods. the factory cutaway plainly shows a long magazine box with a sheet metal spacer in the back to act as filler for shorter than 375H&H ctgs. there would be more than one of those. actually, per the parts list are a 308 lgt, 30-06 lgt, 375 lgt and a couple of oddballs. i can't find any evidence that the push feed models used any but a common bolt stop thruout the cartridge range.

some "gunsmith" wanted $2300 to do this mod, i could do the whole thing in my garage. not counting bbl install i could do it in my living room with a screw driver.

quote:

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Originally posted by vapodog:
If it trips your trigger you can have it rebarreled to .375 Taylor and that equals the performance of the .375 H&H and no changes to the action is required.....but now you have a wildcat.

Here's a better thought.....spend a "C" note and have the .300 mag glass bedded and barrel free floated and see if the accuracy improves.....I'll lay even odds you'll be shooting in the 1" range.....and won't want to trade.

Then watch the gun shows and pick up a good .375 H&H and now you have two guns!!!

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VD:
Have bedded the action, tried bbl pressure to free floating (liked about 5# pressure), every load in the book, etc. and best I can get is 1.75 moa. Granted this is acceptable hunting accuracy, but not what I expect from a rifle. About made up my mind a new bbl (or rifle) is about the only solution or accept mediocre accuracy.

I do like the last part of your suggestion, though. Two guns are always better than one!

Regards,
hm

quote:

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Originally posted by willmckee:
got curious and looked in "the rifleman's rifle" by roger rule. quote: "...the pre-64 utilized three receiver types, the 'new style' had only _ONE_ for all cartridges. this was 1/8" longer overall, designed for the longest chambered cartridge, the 375 H&H magnum, rather than the 30-06 as in the pre-64. ....The magazine well length for the 'new style' was 3.72" while 3.50" for the standard pre-64. (to gain H&H magnum capability, the well for the pre-64 was opened forward into the locking seat to 3.70")."

as i said, no action mods. the factory cutaway plainly shows a long magazine box with a sheet metal spacer in the back to act as filler for shorter than 375H&H ctgs. there would be more than one of those. actually, per the parts list are a 308 lgt, 30-06 lgt, 375 lgt and a couple of oddballs. i can't find any evidence that the push feed models used any but a common bolt stop thruout the cartridge range.

some "gunsmith" wanted $2300 to do this mod, i could do the whole thing in my garage. not counting bbl install i could do it in my living room with a screw driver.

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OK...so I picked up my .338 Win Mag classic and a loaded .375 H&H shell and looked it over and yes it appears as if I removed the spacer in the back of the magazine the .375 would fit into the magazine and feed and eject even with loaded and unfired ammo. There's very little extra room but it seems as though it would work.
I bow to you willmckee

i had actually gone thru that exercise twice lately which is why was pretty sure. once on the classic action 458 just wondering what would take to make a 404 jeffery on it. the 2nd time, a coworker had (still has i guess) a push feed 300winmag he was trying to sell and i didn't need another 300mag but was looking at it trying to figure out just what i could do with it so i'd already measured, etc, gone thru the parts lists. didn't need yet another unfinished project so passed. but it'd been a couple years and i couldn't remember exactly what i'd found then. rules book of course predates the short action push feed when he says "one receiver".

the other thing abt the post 64's being "generic" is cheap at the same time is a handy idea. there are no feed rails; rather the sheet metal mag boxes (and other companies do this too) incorporate feed "lips". change calibers/ change mag boxes. no risky work on the action itself.

The .300 action is the same length as the .375 there is no cutting out, hardening or other monkey business needed . Knock out the spacer in the magazine box , and cut back the bolt stop and you have your .375 length action . You may need a different follower or need to tweek the lips of the magazine to keep the skinny shouldered H&H rounds from popping out of the magazine. Or all these parts are available from Brownells if desired.

I view this as quite a practical conversion because a new M-70 in .375 is now right up around the 1000 dollar mark . For less money invested , counting the value of the .300 plus rebarrleling , you will get a better quality barrel and you can select the contour you prefer , instead of having to settle for the truck axle clone on the factory gun .

In my experience , the push feed M-70 is about the most reliable low dollar action you can lay your hands on.........

Vapodog,willmckee, sdgunnslinger:
Thanks, guys for sharing your knowledge/experience!

I had not actually gotten around to measuring action/magazine yet but thought the action might be same. Sounds as if this might be economically feasable after all.

I had a wonderful shooting push feed 375 which I gave away and found I really missed it.

Think it's time to do a bit more research on this project.

Regards,
hm

quote:

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Originally posted by willmckee: just wondering what would take to make a 404 jeffery on it.

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For equivalent power the .416 Rem makes more sense but I set a .404 Jeffery case and a .375 H&H case (both loaded rounds) and Walla: same length!!! Yes the 404 Jeffery is very doable and here's a little trick.....resize the RUM cases because the case heads are rebated so you don't have to do any bolt face alteration.....I personally like the 404 Jeffery head stamp so I bought Norma cases and turned the heads to the same size as the standard magnum.....walla: again this works. I'm feeding that thru a 1999 action that's designed for the 375 H&H.....again I think this is very doable in the 404!!!