You Big Bore Magnum fans will love this....

I rescently had a talk w/ a long range shooter who had several custom rifles. He showed me a few cases and bullets from one of his rescent projects. His smith had taken the .375 RUM case design and necked it up to .458. He was getting 3200 fps w/ Speer 350 grn. Hot Cores and he also had several heavy weight loads in development too.

W/ the 350s he was achieving 1.5" groups at 100. I don't know what he was getting w/ the 600+ grn rounds.

He said recoil was almost unbareable w/o a Muzzle break. I feel he will probably have one on before long. I dont understand why anyone in their right mind would want to develop rounds for that rifle w/o getting a Muzzle break installed but, to each his own.

Sounds like it would be a great cart design for you "Dangerous Game" hunters.

Good Luck and God Bless!

Reloader

It's really nothing new, there was the 460 G&A, and then also Saeed's PH Roy that made the 458 Vincent. Both 404's necked up to 45.

The one thing that has been discussed at length is that the shoulder is marginally large enough for reliable headspacing, ok in a wildcat, but not really enough for a production round. Asside from that shortcoming, the case is ideal for driving a 500 gr bullet at 2200-2300 fps at reasonable pressure levels.

I thought the whole concept sounded kind of dangerous w/ the speeds he was talking. The only way you could produce speeds in that range would be w/ a moderately fast powder and ther is no telling what the pressure would be.

At lower velocites it would probably be a stellar performer.

Reloader

A look at Quickload shows that it would take pressures in the 120,000psi range to get 3300fps from the Speer 350 with a case capacity of 120gns.

I like the idea though. I just wish that the RUM case was large enough to neck up to 475

Paul,
Since I sold the 416, I now have
.375, .458, .510, and working on .550

OH NO!!!...
looks like a .423 might be missing...

oh damn... i've got a LONG bottom metal..

but I might want a 470 mbogo!!

jeffe

Right on...you need 127 grs of water capacity to drive a 350 gr bullet 3200 fps, so that means 134 grs of any propellant suitable for that expansion ratio. You just can't find that capacity in the 375 RUM.

A more practical, and much discussed, round is the 416 RUM which has an adequate shoulder, falling dead center on the H4350 burn rate. Use a true magnum length action like the CZ 550 and a 1 in 10 twist rate and you are going to drive a 500 gr .416 to 2400 fps. The 350 gr 458 at 3200 fps nets 41% more knock down than the 375 H&H with 300 gr bullet....the 416 RUM at 2400 fps and 500 grs is 137% greater.

Hi Reloader,

The 416 RUM would be an awsome cartridge!!! I talked with Remington and tried to get them to develope it in a comercial round but so far no luck.

Hawkeye47

Yes, I think the Mbogo would be very nice, but I kind of like the idea of affordable RUM brass.

That haphazard micro-rebate of the 375 RUM rim makes it less attractive than 404 Jeffery brass for wildcatting. The 404 Jeffery Norma brass is a consistent 0.540" at the rim diameter. The various RUM brass that I have measured is 0.532" to 0.535", a bit sloppy and variable.

The 416 Dakota (full length 404 Jeffery necked down to .416 caliber and blown out to 30 degree shoulder and shorter neck) is available but in the doldrums with Dakota Arms. Seems that most customers get their boats floated by the 416 Rigby or the 416 Remington, and the 416 Dakota is left high and dry.

Instead of the 416 Dakota, Dakota Arms is now pushing their 2.550" cased 404 Dakota as getting 2400 fps with the .423 caliber 400 grainer, a shortened and "improved" .404 Jeffery. I beleive them, but what is the advantage of that cartridge over the standard 404 Jeffery? 0.3" shorter when loaded with the same bullet.

This would be an advantage in using shorter actions (uncircumsized Mausers and stainless Ruger MK II's, for example), but the magazine box still ought to be widened properly for the 404 Jeffery head size, eh?

There is no sane reason to push a 350 grain .458 bullet to 3200 fps, but a 460 Weatherby might be less likely to explode in so doing. The 458 RUM would be a poor replacement for the 460 G&A.

Ron,
404 dakota sounds pretty cool for the bajillion mausers out there.. heh.. GMTA means that 3.35" rounds and mausers are fantastic (550 express)

jeffe

Jeff,
Agreed. The 404 Dakota deserves more notice. It is the ultimate "Short Magnum" big bore. RCBS makes the dies that Dakota sells for $109. Jamison (maker of .408 Chey-Tac brass) makes the 404 Dakota brass, right across the road from Dakota in Sturgis. JGS makes the reamer. The Dakota 76 rifle in 404 Jeffery as a take-down would be sweet, and surely less than 10K$ ... or any old Mauser with the proper box and barrel would be more my style for moving 400 grains at an easy 2400 fps.