QD,
the Weatherby radiused shoulder is pretty universally regarded as a unique selling point (aka 'marketing gimmick') by those knowledgeable on cartridge design matters. Roy Weatherby was a remarkable man and all power to his (late) elbow on generating business and making customers happy, but he sold a lot of rifles and ammunition on the back of some technically dubious claims for both internal and terminal ballistics.
At a time just after WW2 when belted magnums were typified by the steeply tapered H&H designs, he was an early innovator in 'factory improved' cartridges - take the 30-40 year old British designs, and remove most of the case-taper to increase powder capacity substantially. While the British cartridges were designed for case-length cordite strands in African summer temperatures and were deliberately conservative in load fill-ratios and maximum pressures, Weatherby loaded his cases up to the gunnels and ran them at what were exceptionally high pressures at the time around the 65,000 psi mark, some batches reckoned to be hitting 70,000 psi even! To allow even more usable pressure, all Weatherby chambers had lots of freebore with a large bullet jump to the riflling built in. Put all these things together and you got some of the highest performing cartridges of the day, and even now. As a great salesman, Weatherby publicly attributed this to his patented case-shape and the 'venturi effect' of the radiused shoulder improving combustion. (Doesn't that sound familiar again now with all the claims about short-fat case shapes?!)
Until recently, Weatherby designs remained 'proprietary' and Norma Precision loaded factory cartridges for the company. They're no longer 'proprietary', but you don't see all ammunition makers rushing to adopt the 'super-efficient radiused shoulder' which tells you something, rather they went a quite different way - short and fat cases, no belt, and headspace on the shoulder, as per the Lazzaroni designs, WSMs, Rem SAUMs etc. Nothing wrong with Weatherby cartridges as sporting numbers, but I wouldn't consider them for precision target shooting.
Frank and others,
If I may add my twopence worth on the belted magnum and accuracy issue, I have a 'bitzer' .300 Holland & Holland Magnum built by a friendly gunsmith out of his spare parts bin - not a single new component except for the Ken Farrel 20-MOA sloped scope rail and the bedding pillars and materials. Winchester P'14 ('Enfield') action, heavy Bishop walnut target rifle stock, 30" Australian Maddco heavy Palma profile 1-12" twist barrel off a .308W prone rifle. Rechambering to the long H&H cartridge 'cleaned' the old chamber and throat out and I got a long-range F-Class rifle for very little money. It was fun for a couple of years and pushed 185/190s out at 3,000 fps accurately, but was soon uncompetitive given F-Class developments.
Given the almost complete lack of shoulder on the old 300 H&H (8 degrees 30 mins shoulder angle compared to 25 degrees on the .300 Winchester Magnum) you have to stick with the belt for headspacing. Norman Clark its builder gave it a minimum SAAMI belt recess and cases are a really snug fit - all to the good! I read all the stuff about belt diameters changing from loading to loading that's in the Precision Shooting reloading manual, and thought it wouldn't apply to me - moderate loads, neck-sizing only, so a good snug case body fit in the chamber, the tight headspace and support on the belt. Brass is new unprimed Winchester, elderly by the look of the 20-case cardboard cartons and the old red on white background Winchester logo, and fantastically consistent and well made apart from the need to debur the flash-holes and uniform the primer pockets.
Anyway ........... everything in the Precision Shooting guide is true! Four, max five firings and the cases are scrap in this chamber. The belts and the case body just above them expand a little bit on each firing. At around firing four or five with my standard load, you get noticeably harder chambering on turning the bolt handle down, then the additional tiny bit of belt expansion on that firing sees half the cases fail to come out without use of a rod or drop-weight. The massive P'14 extractor claw cannot extract them such is the tight fit of the belt in the recess, but pulls right through the rim. There's nothing else wrong with the cases - tight primer pockets etc - and they'd probably be fine still in a loosely chambered sporting rifle.
All this brought home to me the disadvantages of relying on that little raised rim at the back of the case. Not surprising either as it was never designed by H&H back in 1910 or so for match cartridges. the intention was to get the positive benefits of rimmed case headspacing but with a well tapered case body up front for absolutely flawless feed and extraction for dangerous game-shooting in the then newfangled bolt-action magazine rifles. British riflemakers had to start making them alongside their 'doubles' in order to compete with Mauser and Mannlicher who were stealing the African rifle building trade with cheaper bolt-guns. It was a brilliant answer to that problem at that time, but this 100 years on, and I wouldn't have another belted magnum now for target shooting.
Incidentally, the 'antiquated' .300 H&H is an excellent antidote to faddism in cartridge design. It has 'everything wrong' - belt, 2.850" case-length, 8-deg shoulder etc, etc. But ........... it's a very, very accurate cartridge inherently and gives identical MVs to Winchester's fashionable .300WSM which by coincidence (or, maybe not!) has virtually identical case capacity and maximum allowed pressure to the H&H. I've had WSM owners tell me their rifles give an extra 100 fps over mine because of 'cartridge case efficiency' and that their 26" barrel sporters will match my 30" match rifle. B*LLSH*T !! Look at any manual and you'll find the two give same MVs for any particular powder and charge weight give or take a few fps if the test barrel length is the same. The same powders give best MVs and results in both designs despite the great difference in their shapes. I'd pit a good H&H against a WSM for accuracy too providing the belt fit / headspace is right and the brass new. As I said, there are many disadvantages to belted magnums in target shooting, but lack of 'efficiency' isn't one of them. Despite the unfashionably long powder column, the H&H gives remarkably small velocity ES values too, a big plus in a long-range rifle. One real advantage I do see in the new short-case designs though is the ability to build rifles on shorter, stiffer actions.
I still have the Winchester .300 H&H and will do some primer tests in it this summer to see if the long case really does need magnum primers as is so often said in loading manuals and elsewhere. Then ............... I'm swithering as to whether I should just scrap it as the long P'14 military action is hardly state of the art in modern rifle design, or to have it rebarrelled to the .300 Remington SAUM with a quality barrel, and see how it does against all the modern kit at long-range.
Laurie,
York, England
