I have a Win 70 super grade 300 mag, and 7mm mag; Conversion to a useful caliber is a sine qua non!
I have all manner of .4 and .5 calibers. Inspired by SAEEDS example, I think a relatively light .375 Ultramag might be the way to go! After all, this is not much different from saeed's .375/404 Improvesd!
Why has no one talked about this conversion? There's all this talk about the 375 ruger viz no different from a 375 H&H; but no one talks about a 375 with the ability to drive .375 350 gr bullets @2600 fps or close! Think of the SD and penetration!

I agree! The 375 Ultra mag is easily the equal of a 505 Gibbs or such other overly large and recoiling rifle!!

.............Last year I had to decide on what I would build up in my CZ and the 416 Rem mag won out over the 375 RUM................But only just ...... //.....,,,.,.,.,,,.../////.,///..,,,./.,/.,

quote:

Originally posted by Indlovu:
I have a Win 70 super grade 300 mag, and 7mm mag; Conversion to a useful caliber is a sine qua non!
I have all manner of .4 and .5 calibers. Inspired by SAEEDS example, I think a relatively light .375 Ultramag might be the way to go! After all, this is not much different from saeed's .375/404 Improvesd!
Why has no one talked about this conversion? There's all this talk about the 375 ruger viz no different from a 375 H&H; but no one talks about a 375 with the ability to drive .375 350 gr bullets @2600 fps or close! Think of the SD and penetration!

Just bought a copy of Nosler's #6 manual and in the technical notes on the 375 RUM, they refer to it as the "most accurate of the 375's"!!!

I've got a CZ 550 Magnum in .375 RUM, 4 down and 1 up, it was tricky to get feeding reliably.

I also have a 300 RUM WinM70 Classic Stainless that will be a cinch to feed perfectly with a rebarrel to .375 RUM: 3-down/1-up, factory box.

Of course the Remington M700 in .375 RUM is indeed a "most accurate" .375 out of the box, as verified with mine, using the Remington Factory ammo with 300-grain Swift A-Frame bullets, at just over 2800 fps in the 26" stainless barrel, if you don't mind a pushfeed.

Still, it is hard to beat a .375 Weatherby that will give 2800 fps with 300 grainers in a 26" barrel, or 2600 fps with 350-grainers.
And accuracy with a well made custom .375 Weatherby can not be beat, even by a .375 RUM, it's a tie.
And you can shoot .375 H&H ammo in the .375 Wby, in a pinch, with excellent accuracy and effectiveness.

Rip, whats the case capacity of the Wby vs the ultramag?
Would you advise the Wby over the ultramag?
Those model 70's are itching to be made into some thing useful!

Indlovu,
If you use the Norma-made properly headstamped .375 brass, 111.5 grains of water to a flat meniscus at the top.

Saeed's .375/404 UA Express is about 119 grains.

.375 RUM is about 120 grains.

The latter two are capable of 2900 fps with handloads, and comparably the .375 wby maxes out at 2800 fps with same bullets and 26" barrel length.

The .375 RUM factory ammo did about 2800 fps with 300grain Swifts in a 26" barrel.

If I build another .375 RUM it would be with the M70 with the 300RUM factory windowed box and follower and spring parts. That is slick with the RUM.

Saeed's cartridge is loaded to 3.8" box length and has no rebate at all on the rim.

The .375 Wby (no rebate but belted) is loaded to 3.6" box length with factory ammo that achieves 2800 fps with 300-grain Nosler Partitions in a 26" barrel, no hype. Near max loads. The CZ box and .375 WBY throat allow 3.8" loads, and I have gotten 2820 fps with H4350 and 300 grainers in a CZ rechambered to .375 Wby, but that barrel is a25" long one with a 14" twist and not the best with 300-grain monometal copper bullets, nor 350-grain cup and core. Need 1:12" twist.

A .375 RUM can be loaded long in the CZ but you need to rethroat it to slightly longer than the short throat of the factory .375 RUM. Of course a 3.625" box length is fine with the standard .375 RUM ammo.

I suggest the 2001 vintage .375 Weatherby throat on the .375 RUM for pressure relief and long loading capability with no loss of accuracy.

You cannot simply rechamber a .375 H&H to .375 RUM, must set the barrel back or get a new one.
You may rechamber a .375 H&H to .375 Wby, quite easily and simply. Of course a new barrel with a pristine throat of purely 2001 .375 Wby vintage would be best.

1:12" TWIST!!!

Here's a visual to help out...



9.3x64, 375 Ruger, 375 H&H, Saeed's 375/404, 375 RUM, 378 Weatherby.

I don't have a 375 Weatherby for comparison.

The 378 must be Rich's favorite 375 cal eh? No replacement for displacement! Sorry Rich, saw that big-azz case and couldn't resist.

Cheers,
Canuck

Saeed's case has a longer neck but the Norma brass he uses gives extra capacity compared to what would come from the thicker Remington .375RUM case walls.

Saeed's .375/404UAE and the .375 Lapua Mag. are both about 119 grains water.
The .375 RUM is only about 1 grain bigger than these, due to brass thickness.

L to R:
.375/.338WinMag (with incipient casehead separation)
.375 H&H
.375 Wby
.375 RUM
.375 Lapua
378 WBY
(pre 375 Ruger archival photo)



The long-nosed bullet is a Bridger-Made Walterhog that is the most accurate .375 bullet I have ever known, even in a .375 Wby, 0.138" for 3-shot group at 100 yards:

you're gonna need better bait than that to get me in. The big Wbee is a good case for wildcatting though, did I ever tell you about the 22-378Wbee AI I built...?

If I ever replace the 375H&H CZ I have it will be a 375 RUM though.

Rich
DRSS
Knowledge not shared is knowledge lost...

quote:

Originally posted by Idaho Sharpshooter:
you're gonna need better bait than that to get me in.
Rich
DRSS
Knowledge not shared is knowledge lost...

I am sure you understand I just couldn't resist.

quote:

The big Wbee is a good case for wildcatting though, did I ever tell you about the 22-378Wbee AI I built...?

That is your famous Eargesplitten Loudenboomer, no? Yep, I heard of it. It had to be done...excellent work!

Cheers,
Canuck

RIP! Are you annealing those cases in your Weber BBQ or what!?!?!?

WHOA!!!

Macifej,
I have better methods now but that worked fine, years ago.

You should see what your SHark brass bullet looks like after it has had four or five #4 lead shot melted into the nose with a propane torch.

Anneal after necking down and before necking up ... and simultaneous to SHark dentistry.

Let's see a photo of your Dental artistry Doc!!

You might want to put a micrometer on those cooked projectiles.

They still measure precisely .395" on the SHark bands man!

I see now that I have to perfect the cosmetics of my technique with such a critic of dentitry as you. Remember, I aint a dentist nor a veterinarian, just an amateur in a little shop of horrors.

Later alligator.

mufasa has used this round, extensively, in africa, to great success... he is in the top 10 of all shooters I have ever seen

I'm having a 375 RUM built by Hein - should take delivery in mid-Jan. It will have a Darcy Echols pattern McMillian fiberglass stock, 24" number 5 contour barrel, single standing barrel band rear sight with recoil lug, and a barrel band front sight. It is going to be my "wet weather" gun. I also have a 375 H&H but my wife has claimed the rights to it.

RIP
I have a .375 Weatherby which I just finished and love. From the magazine articles I have read, it appears the .375 Ruger is getting about the same velocity as the Weatherby even though the case is a little smaller. Is this your experience also?

Whether the .375 RUM is neglected or not as a cartridge, the Remington brass makes fabulous .404 Jeffery cases. I've reformed over 200 of them to date without case losses of any sort.

quote:

Originally posted by Oldcoyote:
RIP
I have a .375 Weatherby which I just finished and love. From the magazine articles I have read, it appears the .375 Ruger is getting about the same velocity as the Weatherby even though the case is a little smaller. Is this your experience also?

Oldcoyote:

There is no way the .375 Ruger can equal the .375 Weatherby.

Anyone getting .375 Wby velocity with a .375 Ruger is way over pressure.

Or he has a 42" barrel and a 100 grain booolit!

quote:

Originally posted by Blair338/378:

Just bought a copy of Nosler's #6 manual and in the technical notes on the 375 RUM, they refer to it as the "most accurate of the 375's"!!!

I agree!

Yes, a Remington rifle with Remington ammo is usually an accurate combination.

Here is my first trip to the range with a new factory M700 LSS, 26" barrel. Darn near got it zeroed with the first 5 shots through it after bore sighting a Leupold 2.5-8X on it at the range.
0.549" for 3 shots at 100 yards,
with 300-grain Swift, factory load, averaged 2803 fps
(270-grain factory load averaged 2935 fps in same rifle):


A CZ with Winchester .375 H&H chromoly take-off barrel (cut off at the breech end to 23" and re-chambered) did a little better accuracy-wise with the same ammo, and surprisingly fast for 3" shorter barrel. It was a custom chamber job with tighter throat and the Winchester barrel may have been tighter than the Remington.
0.410" for 3 shots at 100 yards,
300-grain Swift, Remington factory ammo, 2780 fps
(270-grain remington factory ammo did 2895 fps in the 23" take-off barrel):


Here is a .375 Weatherby with handloads using Bridger copies of the early Walterhog bullets:


There are no flies on .375 Weatherby accuracy!

After seeing how fast my short-throated 23" .375RUM was I had the throat changed to a .375 Wby throat (2001 version). CZ action, Dakota magazine follower and spring, Winchester barrel, Remington chamber, Weatherby throat: Yes I am a redneck! We do not let perfectly good spare parts go to waste!