Fellow members,

I decided to modify my main hunting rifle as follows. I will be using a Winchester M70 classic stainless in 375H&H, and re-barreling it with a 24 inch PACNOR barrel chambered in 375 RUM. The action will be trued, NECG sights will be installed, the whole action and barrel will get a matte cerakote finish. I'm asking for advice from people who have had this conversion done. If you have any input or suggestions, please feel free to post a reply.

Cheers,

Maurice

P.S. Also posted in the Big Bore section.

There wont be a lot to modify, most likely open the feed ramp some and the ejection port on the inside of the rear bridge area will likely need to be opened to allow the fatter case to kick out and not hang. You might have to cut the top of the mag box to allow more case to be under the feed rails, if you can look at a classic win in 300 ultra to see what iam talking about its hard to explain. The factory ultras also have a cut out of the left feed rail to allow the case to snap under the extractor quicker then a 375 h&h not a lot to do but if you never done it before or dont have any experience any feeding it could look very complex

before any modification I would take some dummy rounds and load them then run them up the feed ramp as far as they go into the chamber just to see what they do if they feed or almost feed it wont take much to get them to feed and you will get an idea of what needs to be removed.

Thank you Mike for all your information. I really appreciate it.!

How about building off a .300 RUM? Seems like that would be an easier and cheaper route that would produce the same results.

At least as of a couple months ago the RUM box and follower were still available from Winchester. About $50-60 for the pair and the rest is tinkering to make it feed and extract 100%.

I would add a Williams steel extractor and bottom metal all Cerakoted to match of course.

Personally, I feel that the factory 375 barrel profile is too heavy. About a #4 feels closer to me. What contour were you planning on?

Hello Brent,

Thanks for your reply. I have a love affair going on with the 375 caliber. I love my 375 h&h, but the reason going to the ultra mag is to get rid of the belt, and to load up the RUM to roughly the same velocities as the H&H, maybe a tad more, but with way lower pressures. I also find the RUM damn sexy, if that makes sense... I always craved big guns

As for the RUM box and follower, I will have to talk to my gunsmith. Obviously the factory plastic follower piece of junk will go in the trash. I saw that aluminum followers were available from brownells, however I'm not sure they will work with the RUM... I also like the idea of replacing the extractor with a Williams... Maybe the bottom metal also. I like the #5 contour myself, and bit of extra weight won't hurt things with this caliber.

By the way, does anyone know what type of material Winchester used for the bottom metal on these M70 classic stainless? Thanks

You won't catch me talkng smack about the .375 caliber. In fact, I'd like to add a M70 Classic SS to my meager collection. I was just wondering why you weren't building a .375 RUM from a RUM actioned M70. Seems like it would be a little easier and cheaper.

Hello Brent,

The quick answer to your question is that I'm a one rifle type of guy. I hunt deer, moose and bear with my 375. Its not needed, but that is what I like

The long answer is that, the fit and finish on my M70 is terrible. Tool marks are present on the rails and different areas of the action. Feeding is ok, but not great. The gun shoots well, however, as much as I like the H&H, I want something new If I bought another M70 in some RUM flavor, I still would have to get work done on it, since quality control at Winchester was terrible in the last few years of production. And at last, I only want one rifle. The Rum will allow me to duplicate hot loaded H&H velocities, with low pressure. That's what I want. And if needed, I can always load it up to the max.