A thinking question for people.

Who came up with the Double Raduis Cartidge Case Shoulder first.

Weatherby?

Winchester?

James Wisner
Custom Metalsmith

I thought that it was first used on a German line of rounds, turn of the century?

I think some of the early Vom Hoff had a double radius shoulder. If Cheechako is listening, he could answer it for sure.
Butch

During the 1940's, Ralph Waldo Miller, a southern Calif. gunsmith tried blowing out the 300 H&H Mag cases to give a straight body and a radius shoulder called the Venturi. The resulting cartridge was called then.300 Miller Freebore, because he used long throats on his chambers to cut down pressure(freebore). The cartridge was taken over by an astute promoter named E. Baden Powell, who called it the 300PMVF- Powell Miller Venturi Freebore. Powell and Miller developed a whole string of cartridges using the Venturi shoulder, and marvelous things were claimed for them. About the end of WWII, Roy E. Weatherby, an insurance salesman and rifle lover, got interested in the PMVF line of cartridges. INSTEAD OF USING THE CONCAVE PMVF RADIUS, HE USED THE CONVEX WEATHERBY RADIUS, NOW WEATHERBY'S TRADEMARK.

A number of experimentors were using a venturi type shoulder including some of the German cartridges. Weatherby came up with the idea of the double radius because it maximized case capacity and made it harder to grind the reamers,therefor making it more difficult to copy the weatherby calibres.

From the pages of:

http://webpages.charter.net/rogngay/MadTownHomePage/

"Weatherby Shoulder Genesis" While talking to Roy Weatherby of Weatherby Firearms we talked about Ralph Waldo Miller and E. Baden Powell two experimenters and wildcatters from the 1940's. Miller developed the Miller-Venturi Freebore cartridge and Powell was involved in the familiar names such as Vard, Inc., Hollywood Tool and Die, PMVF, and CCC. (PMVF) Powell Miller Venturi Freebore and (CCC) Controlled Cartridge Combustion. Weatherby took the PMVF cartridge case, added a second radius and formed the case with the double radius shoulder. With smoother corners at the shoulder and neck junctions of the case gases supposedly flowed from the case without creating as much back pressure

When did Roy Gradle make his 7mm Express?
Butch

Many of the first self contained cartridges had shoulder and neck junctions that were rounded. But they were not as pronounced as you find on the Weatherby cartridges and it was done more to facilitate feeding and case forming than for any ballistic advantage.

The very first modern, high intensity cartridge that I'm aware of with a true double radius shoulder was the 275 H&H Magnum, which is now nearly 100 years old. The Weatherbys are a spitting image of the 275 design and I'm sure Roy W was aware of it when he designed his own series of cartridges.

The PMVF and other venturified cartridges are really a single radius design.

Butch is correct about the 7mm Vom Hofe SE having a unique shoulder. But it is more of a double angle than a double radius. What makes it very different is that the factory ammuntion had a conventional shoulder but the chamber was cut with the double angle. As I understand it, the intent was to reduce pressure peaks that this very hot cartridge generates. Not every 7 X 66 rifle has this chamber. Butch tells me that he just acquired one that is conventional in every way.

Here's a photo of the Vom Hofe, before and after firing. The fired case has had a bullet seated in it but I'm not positive that these cases were ever reloaded. The majority of shooters using them were aristocrats who shot factory ammunition almost exclusively.

Ray

Good information.

Least we forget about G L Herters Triple Ram Magnum also for unusual shoulders.

Look at the specs on the 25-35 WCF that Winchester brought out in 1895. It has a Double Raduis Shoulder.

Seems that things will always come around every so often in History and repeat themslefs.

Have a Merry Christmas.

Jim Wisner
Custom Metalsmith

quote:

Originally posted by Cheechako:
Here's a photo of the Vom Hofe, before and after firing. The fired case has had a bullet seated in it but I'm not positive that these cases were ever reloaded. The majority of shooters using them were aristocrats who shot factory ammunition almost exclusively.

Ray

Ray,

That rim looks like it is rebated. Do you know the base diameter of the brass or what it was based on?

Thanks,

Ray probably hasn't got out of bed yet. My 7x66 Vom Hoff is factory brass from W. Germany. I will measure it when the shop warms up in a little while.
Butch

I'm awake!!!

Both of the cases in my photo are factory 7x66 SE. I'd have to dig them out again to measure the base but maybe Butch will beat me to it if he can find his shop through the blowing snow.

Ray

The web measures .540 and the rim .502. These are reloads and may vary a little. As I posted my brass is headstamped 7x66 V,Hofe SE
Butch