I've got a new 375 H&H in a model 70. I thinking of trying a Ultra. Should I run a reamer in it? Will it feed with out much mod?

505ed

The only thing you will get from a RUM which you will not get from an H&H is flatter trajectory. But the H&H is pretty flat, equalling a 30-06 180 grain load.

To change your gun to 375 RUM you need to ream the chamber, open the boltface, open the extractor, file the fails and possibly adjust the feed ramp. Maybe replace or grind on the ejector. That might be $400 to $500 worth of work.

And when you get done, the Winchester will be worth half of what it is now.

Better to leave it alone.

I'd second it, to leave it.

If you're bent on a bit more speed then have it punched to either 375 AI or the 375 Wby. I've shot them both and they'll give you a bit more.

Just a thought.

MD

I'll keep it as is. I'll do that 700 LSS in a 7mm Ultra. I hate that thing.

505Ed

There is an Australian who posts as John T and he had a Model 70 Stainless 75 rechambered to 375 Ultra.

I seem to remember that the rifle worked fine with just the rechambering. If you do a searc on 375 Ultra you should turn up some of his postings.

I don't know why the bolt face would need to be opened as 500 Grains suggests as the Ultra and H&H have the same rim diamter.

I don't think such a conversion will make too much difference in the game fields but the 375 Ultra will allow you a lot more leeway to play about with loads. Saeed uses a pair of 375/404 Improveds which is essentially the 375 Ultra.

If your rifle was a Remington African Big Game Rifle or African Plains Rifle I would prefer the 375 Ultra and ditto if it was a HS Precision. But for a 375 H&H I like the CRF type action...they just seem to go together.

Mike

505: I'd leave it as is. I myself was leaning towards a 375 Weatherby, almost the ballistic twin of the Ultra. However, this past June in Zimbabwe I saw my friend take a gorgeous kudu at a measured 354 yards with his 375 H&H loaded to 2550 fps and 300 grain Swift Aframes ( I know, I loaded and tested them myself) that are not noted for the ballistic coefficient. He held right at the top of the back and wham, he dropped like a stone. That cured me in a hurry. I think if I went to the 300gr TSX I could probably wrestle a bit more in trajectory, but I have to admit that shot was impressive. jorge

500 grains has given you sound advice, leave it as is.

As Ray and 500 Grains said the only PRACTICAL advantage in going to the Ultra is if you plan on using it at over 350 yds.

465H&H

465H&H

I think the 375 Ultra will offer an easier route to 2500 plus with bullets such as the 300 grain Barnes X

Actually, the 375 Ultra relates to the 375 H&H in the same way the 416 Rigby relates to the 416 Remington. Even rimless Vs belted

Mike

I own sort all of the above--.375H&H, .375 Ackley Imp., and .375 ultra. You may want to go the .375AI route but I wouldn't start with a.375H&H and try to go to an Ultra. Having said that IMHO the .375 Ultra is a big step up from the .375H&H.

After observing Saeed kill a couple of dozen buffalo with the 375/404 I have developed a new respect for the faster 2375s, until you have seen them work, you should be careful about such statements as you gain nothing from the added velocity...A monolithic 300 gr. at 2700 to 2900 FPS kills buffalo as well as a 468 Lott it seems...

I would not recommend the conversion unless you can get a RUM magazine..the 404 cartridge is a hard on to make feed...sell your 375 and buy a new 375 super magnum....

Jeez, I got fat fingers, guess I need to review my posts in the future, nawwww I ain't gonna do that!

I just got my 375 RUM back from Bill Wisemann. Factory 300gr A-Frames are clocking 2905fps 15' from the muzzle (26" barrel). Accuracy was one hole from 70 yards. Did I mention that was a factory load?

I would start with a larger action if you were going to go the Ultra Mag route. I have one on a remington action...there just isn't enough room to get it to feed properly.

Remember that the .375 RUM has a neck slightly longer than the .375 H&H, which is handicapped by a too short neck. Both cartridges are the same length.

So ... just running the .375 RUM reamer into a .375 H&H chamber will not clean up the neck/shoulder junction. You will end up with an apparently radiused neck/shoulder juncture instead of a sharp RUM angle.

You have to set the barrel back at least one thread, and might as well rebarrel.

The .375 Wby will clean up the .375 H&H chamber with no monkey business required.

I have done all of the above, and so much more ...

The only good setup for a RUM cartridge with its rebated rim would be a vertical in-line magazine stack like they did with the .425 WR.

quote:

Guns, Politics, Gunsmithing & Reloading Big Bores 375 ultra

Gringo P, Does your .375 Ultra have Wiseman's detachable in-line magazine? I have used mine on a lot of African game and I really like it.

[QUOTE]Originally posted by Atkinson:
After observing Saeed kill a couple of dozen buffalo with the 375/404 I have developed a new respect for the faster 2375s, until you have seen them work, you should be careful about such statements as you gain nothing from the added velocity...A monolithic 300 gr. at 2700 to 2900 FPS kills buffalo as well as a 468 Lott it seems...
QUOTE]

HMMM. Old dogs DO learn new tricks.

Kind of shocked to hear that, Mr. A.

Overall, which do you go for, the Lott or the Ultramag/Weatherby 378?
Recoil? Overall?

G

Hey Ray, you're starting to sound like Roy Weatherby .You want a "hot-rod" 375 get a 378 Weatherby. Sorry 500grains! jorge

505ED,

Had that exact thing done. Mine was a M70 Classic Stainless in 375 H&H - CRF model. As what RIP said the chambers on 375H&H rifles are pretty sloppy so even the RUM reamer does not clean it right out & you do get a Weatherby type shoulder. If you want to get the "proper" RUM shoulder you probably loose about 1 inch of barrel length.

Shoots brilliantly though in spite of that & I would not want the barrel any shorter. Feeds OK without a RUM Box just some bending of the spring. My follower is the old type without the scallop.

I would get a RUM box or will get one made now that I know its a keeper. Its awfully tight with 3 down.

I think the RUM has a place with 300gr monometals & heavier 375 bullets. It does not seem overbore when the best powders seem to be AR2213SC/H4831SC and AR2209/H4350 unlike some of the RUMs the 7mm in particular.

If you want to be practical really stick to the H&H or if you must the 375 Weatherby. In my case I already have another 2x 375H&H's so the decision was easy.

Recoil is another matter - mine weighs 9lb 13oz with scope. I am not going to tell you its a slow push and all that bullshit! It kicks and quite hard, not a little bit more but a lot more than the H&H. But recoil is subjective and that is MHO only.

I think its a worthwhile conversion but if I had only 1 375 it would not be a RUM.

Also if you look in the Nosler Manual they now use the RUM for 375 bullet testing as they consider it more accurate.

Regards
JohnT

JohnT,

I just pulled the stock of my 700LSS. I will pull the barrel and start. I'm going to keep the M70 as is hell I might sell it one of these days.

I'm going to order a Pac-Nor 27" barrel, that will end up 26" and a Mcmillan Marksman stock. It shoud come out about like my 340 WBY (about 10lbs).

THats my plan and I'm sticking to it (right now)

The 375 RUM is better than the H&H if you are a handloader. If you like the H&H performance load 'er down and enjoy the low pressure and reduced recoil. The upside in velocity and power is always there...in small increments...when you want it.


Whether you buy it new or mod an H&H is the REAL issue.

[QUOTE]Originally posted by Sabot:
The 375 RUM is better than the H&H if you are a handloader. If you like the H&H performance load 'er down and enjoy the low pressure and reduced recoil. The upside in velocity and power is always there...in small increments...when you want it.

how is the accuracy on the downloads in 375? what are your load recipies? thanks!

Boom Stick,

I have never loaded for a 375 RUM but have down loaded the 378 Wby and 460 Wby to around 375 H&H and 458 Win ballistics without problem.

In the 460 85 grains of 4064 did just over 2000 f/s with 500 grain Hornadies, no fillers and top accuracy. That load is about 20 grains under a top load of 4064 with 500 grainers.

Loads in the mid 80 grains of Vrget or 4064 do a bit over 2600 with 270 grain bullets in the 378 and that is about 10 grains under top loads with those powders.

The 375 RUM would be easier to deal with than the two bih Wbys because of the smaller cases capacity and the absence of the huge freebore of the 378 and 460

Some people will tell you that these big cases don't load back and then the same people go and sing high praise for the 416 Rigby loaded back to 416 Remington

Mike