Home Forums Hunting & Shooting Ask The Gunwriters Weatherby Double Radius Shoulders

Looks like the double radius shoulder causing short case life myth has been debunked.

On the flip side, I've often wondered the reason for the double radius shoulder in the first place. Is it a derivative of compressible gas dynamic theory (jet/rocket science) that says subsonic gas flow is more efficient over smooth edges? The idea being a bottle neck rifle cartridge is analogous to the converging/diverging nozzle of a jet/rocket engine where gas flow is subsonic in front of the nozzle and supersonic downstream of the nozzle. Of course this analogy breaks down for straight wall cartridges.

Any campfire historians out there know the real inspiration for the Weatherby double radius shoulder? Serious question. I can't imagine RW coming up with the idea out of thin air, but who knows, maybe he did.

I have noticed loose primer pockets, ejector marks, etc with Weatherby factory ammo. Most of it silver box and earlier.
Never had an issue with split necks.

I fully expect it was derived the same way the foreend tip of contrasting wood was envisioned. Weatherby was a doodler when talking on the phone. He always had a pen and pad and scribbled stock designs during his phone calls. I would not be surprised if he simply scribbled the radius design during a phone call one day and then followed up on the concept for no other reason than exploring a potential marketing concept.

Don't forget this was the same era that Keith was writing about duplex reloading which is said to have confused the German's during an active war who read, followed and blew themselves up whereas Keith was actually threading internal primer tubes into his cases to theoretically permit the primer spark to move forward into the case before ignition so that powder burned forward and backwards to the case head. His term "Duplex", was incorrect technically, but he was famous enough that he would write and it would be printed. What this means is there was poetic license in the gun trade back then where as today's market is far more savvy.

The radius-ed shoulder was developed in the 1940s in Germany and the US simultaneously. The PMVF, Powell Miller Ventrified freebore became the CCC cartridges Controlled Combustion Chambering. Vom Hoffe and the German military experimented with a couple of variations. Powell and Miller I think were first in Ventura California and then moved shop to Hollywood, I believe they became the Hollywood gun shop that made dies and presses as well as custom rifles.

Roy Weatherby was no doubt influenced by their work, in the 1950s he developed the double radius shoulder, the early ones had been single radius but had radius-ed the neck and shoulder but not both. PMVF and CCC gave Roy the idea for free boring the chamber as well. The double radius allowed Weatherby to patent and trade mark the design.

They claimed to believe that the radius acts as a venturi tube to accelerate gas flow. It was also a marketing feature and made it more difficult to copy by other gun smiths before it was patented. Testing has proved this not to be true but has shown the shoulder angle of around 30 deg. to produce more uniform pressures which is signifigant when running near maximum pressure.

CCC 30-06 Imp. http://www.cartridgecollector.net/30-06-ccc

Here is an old thread on the topic where I made the same points: https://www.24hourcampfire.com/ubbthreads/ubbthreads.php/topics/3571724/1

Roy used the "Powell- Miller Venturi Freebore" theory to design his cases and chambers. My meager understanding is smoother gas flow starting the bullet and more acceleration with the long 3/4 inch freebore section before engaging the rifleing. With a faster bullet there is less of a pressure spike upon engraving the bullet. That's my story and I'm sticking to it. Right or wrong. JM

Thank you all for sharing your personal experiences. Excellent news that it's a non issue.

We pay $170 for 50 Norma unprimed cases downunder and consider ourselves lucky to get it and that's the old "discounted" price!!!

Regards
JohnT

Well there you go. Thanks DB for the info. Makes a lot of sense.

DBoston,

P.O. Ackley also claimed to have encouraged Weatherby to use longer "freebore". No doubt there were lots of influences--all (as was typical of the time period) concentrating on getting the absolute top muzzle velocity.

But the powders back then were also more limiting. IMR4350 was by far the slowest-burning rifle powder when it was introduced in 1940--and made the Weatherby rounds possible. (Actually, in a bit of trivia, it actually appeared in 1939--but wasn't distributed to the public until 1940. But in '39 you could drive to the DuPont factory and buy it. Don't think any powder company offers that option today for handloaders.)

Of course, after WWII handloaders could buy "war surplus" 4831, which was slower yet.

The only Weatherby I’ve had experience with is the 257. I noted that brass only grew by .004” on the first firing. ( rom to shoulder). I thought this pretty good.

The Winchester and Remington belted mags would grow up to .020” on the first firing. Not so great for case life.

I seem to recall that Weatherby rounds headspace on the shoulder rather than the belt ( correct me of on wrong) . A definite plus for case life.

JB & all, I love the gun trivia. If only Jeopardy had a category for gun geeks and my memory worked faster I could possibly win a new Tesla, or better yet a .256 Newton. I always thought of the 257 Bee as a Californicator round until I got one, now I really like it and appreciate the history too. It is a classic.