.375 Rem Ultra Mag anyone?

[Geno]

Anybody bought, used or otherwise had an opportunity to try this one out? A buddy has a 300 Ultra Mag, my brother has a 338 Ultra mag. I've been able to try them both out, but now they've been topped and have a big brother. Got me to wondering what this beast would be like to shoot. I don't have any need for anything this big other than the big boys sure are fun to shoot.

[sideironjohn]

Yeah, it do look like a boomer.
Nominally the same size case as the blown out Jeffery, it ought to be about the same ballistically as a 375-404 cat.
More than I need, for sure, and from what I understand, the bigger the case, the trickier to "download."
Be an excellent elk sniper, though, if one were so inclined.

[Lvl1trauma]

I had one built a few years ago on a post 64 winchester I bought on close-out at Wally World. I killed a 200+ lb. mulie doe at about 70 yards with it using a Sierra bullet. Don't remember the load or bullet weight. Not real impressed with terminal balistics. I am sure the bullet was too heavily constructed for the game. It has a Vias brake on it. Haven't shot it in about a year- I robbed the scope off of it and put it on a .450 Marlin. It was a handful and certainly got other people's attention if they were standing by you when you touched it off. I need to get another scope because I really like the caliber.

Beau

[VSSF]

He also has the .300 ultra mag too.He doesn't have a scope for the .375 yet though.But should have it by this weekend ,I'll keep you posted.

[Robert]

....If anybody dosent like the recoil in the 338 or 375, I'll trade you my 300.  I sure wish they would come out with a 350 Ultra-Mag....now THAT I would really want.  I am sort of having a love afair with 35 caliber bullets.  They are just SO pretty.
  Another thought about an earlier post about downsizing the loads.....It is Very easy.  I have used XMP 5744 with 200 gr G.C. cast bullets loaded to 2043 fps.  I havent shot anything with them, but they work excellent with that powder.  Accurate Reloading has extensive reduced load data with this powder, they list a 180 gr cast bullet all the way down to 1604 fps.  They also have loads for the 338 UM, but nothing for the 375 yet.

[sideironjohn]

Robert, I'm having what is essentially a 350 Ultra made up for me by John Ricks as we speak. It's based on the .404 Jeffery and should be nominally about .005" smaller at the base than the Ultra, depending on which lot of brass you have, and a 35* shoulder (don't the Ultra's have a 30*?). I had the reamer designed around Norma brass, with tolerances at about half what SAAMI holds, hoping for high accuracy, without sacrificing feeding/extraction. The reamer throat is cut for a 280g A-Frame seated to max COL of 3.6". I should have no problem "downloading" the A-Frame to 2850 fps or so, But I plan to stay right around 2800, depending how my shoulder likes it! I suspect I could push a 310g Woodleigh to somewhere awefully close to 2800fps if I were so inclined. Case capacity is about 119g of water.
Then there's the 360 Imperial Magnum, which is being chambered by some guy out in VA, I think, among others, and it's very similar.
And Z-Hat has their 35 Ultra Cat, which actually IS the 358-300 Ultra.
You might check with them if you're looking to keep costs down, since they already make their own dies.
What you need is a switch-barrel! :grin:

[Lawdog]

sideironjohn,

Question!  Isn't the .350 Ultra the ballistic twin to the .350 Rigby?  From what I've read about the  .360 Imperial Magnum it too is the ballistic twin for the .350 Rigby.  Just wondering if you had heard/read anything comparing the three?  Lawdog

[sideironjohn]

No way. I haven't heard anything comparing the three directly, but a quick look at case size is telling.
The case dimensions of the 358 STA is:
Base .513", shoulder .495", body 2.405", case 2.845", COL 3.6.
The Rigby looks like this:
Base .528", shoulder .45", body length 2.25", case length 2.75", COL 3.6".
360 IM looks like this:
Base .544", shoulder .53", body length 2.339", case 2.83", COL 3.6".

The Rigby's water capacity is about 88g, the STA about 101.5, a 350-300 RUM I made up is about 112g, the 360 IM about 115g, my 'cat about 119g, and then there's the 358 RG (358-378) which holds somewhere around 126g!!
The Rigby actually holds about 3g more water than the Norma, but the Norma doesn't have the loooong neck, and so they are probably the closest to "twins" of the bunch.
That Norma is no slouch, either.
The Whelen holds about 70g, and the 35-348 Imp holds about 91g, for comparison.
Every one of these cartridges has it's place, and there isn't a one I've mentioned that I wouldn't love to own (except the Imp Mag, since I have my own, of course!)

[Lawdog]

sideironjohn,

Thanks for the info and the data.  I have been thinking about building a .350 Rigby as I already have it's two big brothers, .416 and .450 Rigby's.  I haven't put in the time I should researching the .350 Rigby due to other problems(home front, clients and the job) taking up my time.  As soon as things slow down the .350 Rigby may end up being a nice project for say 2004 - 2005.  Thanks again.  Lawdog

[Lawdog]

recoilpad,

Good question.  I reload all of my ammo by necking up .416 Rigby brass.  The necks a bit short at first but after a couple of times firing cures that.  There is a European company that loads .450 Rigby but I'll have to look the name up for you.  The one thing I remember is that they are not cheap.  If anyone that read this knows of a source of factory loaded ammo for the .450 Rigby please let us know.  How do you like your .450 so far?  Mine is built on a Ruger M77 Magnum action.  Lawdog

[Lawdog]

recoilpad,

Two of my favorite loads are;

A Hornady 500 gr. RN-FMJ ahead of 105.0 gr. IMR-4895 for 2,437 fps., groups 0.907".  The other is a Hornady 350 gr. RN-SP ahead of 103.9 gr. IMR 4064 for 2,729 fps., this one also groups under 1".

I really like my M77.  It started out as a action I got from a gunsmith friend and had him install a Shilen Match Grade barrel cut to 25".  While he was at it I had him install Express Multi Leaf  rear sight and a hooded ramp front sight.  I too installed a C&H Research mercury recoil reducer in the stock so that the whole thing weights 10 lbs. 14 oz. including sling.  What I like about the Rigby cartridge is you can load it up to velocities near those of the .460 Weatherby or down to the .458 Win. Mag. velocity.  Lawdog