So question for you guys. I have become enamored with this round. Will this round fit in the remington actions that were made for the 300 ultra? What about bolt face?

Same. Same.
May need follower and magazine from a belted case.

W

Thanks woofer, local guy might be willing to part with an action for cheap. Have to make him a offer.

Rails are wider, RUM's vs. std. Mag 700's.

I know you have to mill the rails back on a std. mag. 700 for a 26 Nosler round to pass into the box mag.

I don't know about reverse engineering, how a std. mag round will feed from a RUM box, set up for fat rounds.

Fat rounds will pass between the rails on a M-70 H&H, so who knows until someone tries it. My M-70 .375 H&H will feed EMPTY cases from the mag as fast as I can cycle the action and without a blip. Got it used, Redneck had worked on it, so how much of that is Redneck, how much is Winchester, I don't know.

Building up rails could be an expensive pain in the ___.

DF

The 375 HH is a unique casing over 100 years old the 300 ultra parent case is the 404 jeffrey. The 300 ultra came out in 1999 rimless and with completely different dimensions. I can't see any one recommending such as same same by woofer.

THe action length, and the bolt face is what I was asking, he was saying that the 300 ultra action will work for the 375 HH i know that the HH takes alonger action and if building a rifle it might actually be easier to go the 375 ruger route but that is not fun.

RUM's are 3.6", full mag length rounds just like the H&H, bolt face is same as H&H and other belted mags.

If it'll feed, it'll work.

DF

While the .404J is the parent round, RUM's are rebated to fit a std. mag bolt face.

I built a .404J using a .300 RUM donor. The bolt had to be opened to accept the fatter .404J rim.

DF

For good gunsmithing advice ask Redneck. Why not just go buy a 300 ultra and shoot it right out the box instead of fooling with fitting and machining for months and still have something that jams or gives you problems later.

I don't want an ultra I am trying to get an action to build a 375 HH on. Local shop has a few cheap.

I had one and liked it. Still have about 100 new brass and some other stuff sitting around for it, looking for a home some day
As above, the 300's bolt face should be fine, but the feed rails may be too widely spaced--you will have to try feeding some brass through your gun to see what happens.

Pick up a used 700 bdl magnum, and barrel it up for a .375 H & H.. that is how I got mine..

I have a 378 which is a 375 on steroids, 20% more power. I've hunted in Africa with it also all over Canada and a Grizz in Russia. If your not planning on any hunts in Africa or going after really big bears you could live with lighter rifle and less costly to reload. Just my 2 cents. But if your bound and determined to have that heavy hitter in your Harem go for it and good luck with the build. let me know how it turns out or even post a few pics while you build it. Not too many tackle such a project.

Wyo, did you have to do anything to the length of the action or will the magnum action work?


378 its going to Alaska Fall of 2017, and then Africa in 2019.

Right on.

54, No. I just bought a bdl magnum rifle, I am not sure of the caliber right now, and had it barreled up in .375 H & H.. I think, it will only accept two shells in the magazine plus one in the chamber.. It should accept 3 in the magazine, but I never really tried to find out why it would not.. I have a .300 Wea. I barreled up on a 700 and it will accept three rds. in the magazine no problem.. It is probably some minor deal that needs adjusted.. If you have a chance, try loading the magazine with 3 rds, and see if all is ok.. For my purposes, I seldom load more than three rounds in any bolt action.. Best of luck..

I only need the round in the tube but I like to have a back up. That makes it easier then longer for the ultra reciever, I can find 700 magnum recievers all over.

A 700 will hold 3 rounds down in the mag like any other belted case based off the H&H case.


If I wanted a 375 on a 700 I wouldn't build I'd just buy a XCR 2 and restock it how I liked.

It works. But your call your gun. I'm sure someone here has a UM and a few standard rounds to run through it..

W

Not seeing anymore XCR's on Remmys website. Their new msrp numbers are a little startling...

W

Another option is to buy a helluva nice Whitworth in 375 for around $800 to $1000. Have one that is wonderful in the hands and shoots very well with 270 Barnes.

Remmys quality control is so all over the place it is hard to say anything for sure, but I have a 257 Weatherby that I built on a stainless 700 that was originally a 338 RUM. Feeds fine!

A guy has to remember that Remington designed the RUM cartridge to fit the 700 action with the bare bones minimum alterations. That's why it usually only takes a mag box change to get them to run when switching from belted mag to RUM. Even if some "gunsmiths" have been known to charge for hours of feed rail mojo and other foolishness.

That said, I have a 375 H&H, 700 Classic barrelled action I would part with that would be an easy route to a good, light weight shooter.

Sask, I know they hold three rounds but for some reason, this one doesn't work quite right, but I never bothered to worry about it.. Two in the mag. and one in the barrel is enough.. At the time I built the .375, the XCR wasn't available!!!!!

My concern, as well.

If you can cycle .375 H&H rounds thru the RUM action without having them jumping out of battery, hitting too high on the barrel face, etc., it may work.

I'd make up some dummies and give it a go. If it doesn't work pretty well, I'd not build an H&H on that action. Welding rails and such will blow the budget, just isn't worth it. Too many other options.

DF

Yep.

And used M-70 Classic, N.H. guns aren't that expensive. Even a push feed M-70 would be OK, aren't expensive, already have a three position safety and a preferred trigger.

DF

I am not sure if this applies to this discussion, but I made up a couple .300 RUM's on a plain magnum action.. The only thing I had to do was get a diff. magazine box. A friend also made one and he didn't change the mag. box out.. Worked fine..

The RUM cases, like the Nosler series, have a std. .534" rim and a .550" case body. When I converted my 7RM 700 to 26 Nosler, the rails had to be milled back for the .550" case to slide between them into the box mag.

M-70 rails will pass a .550" wide case between the rails without modification.

The .300 RUM's you made up on plain magnum actions, were they 700's or 70's.

DF