27 July 2011, 19:29
ramrod340Back in the 1930s a smith in Okahoma built designed a couple cases. The 276 Dubiel was basaed on the 275H&H case and I believe a touch smaller than the 7mag. He built a 280 Dubiel based on a full length 300H&H case but used .288 not .284 and got no commercial support. Non of my easy to find reference data as the exact dimensions of either. They are listed in Cartridges of the World.
Remington also mentioned them and several other 7mm options in a 1988 article on the 7mag.
As to your original comment about pressure issues I've loaded a 7mag for more years than I care to think about and NEVER had a issue.
Here is the articleRemington’s Biggest Seven
by Wayne van Zwoll, first published in Bugle, Spring 1988
Is seven the lucky number for elk?
For a long time now Remington has been trading on the number seven. It's been a lucky one for them. The 7mm Remington Magnum in the 700 bolt rifle started it all, and for elk hunters these are the numbers that still matter. So for now we'll forget the svelte Model Seven, the efficient 7-08, the other sevens that Remington sells. For a few minutes, let's explore the big seven.
It began a long time ago, really, with the smokeless 7x57 Mauser. Developed for military use, it was adopted by the Spanish army in 1893. It was not the first 7mm, but it was the first modern 7mm suitable for hunting. It is still a fine hunting cartridge. Shortly, though, shooters started thinking about ways to improve it, to design a more powerful seven.
About the turn of the century in England F.W. Jones designed a 7mm cartridge for Eley and Sir Charles Ross. It was called, inappropriately, the .280 Ross. It was mated to Canadian Ross straight-pull military rifles in 1906 but was soon acclaimed by hunters who wanted to reach far and flat with fast bullets. The big rimless case was pretty well designed, and even with the powders of the day, 160-grain bullets could be driven to 2900 fps. The bullets were, incidentally, .288-inch in diameter, not .284 as 7mm bullets are now.
The Ross killed thin-skinned game quickly, but its bullets lacked penetration on big animals, mostly because they weren't built for big animals. Some hunters used the .280 Ross in Africa and got killed by big animals that didn't die quickly. Consequently the cartridge got a bad reputation. A little prudence would have helped both the hunters and the .280 Ross.
Believing not all shooters to be so naive, the people at Holland and Holland developed a .275 Belted Rimless cartridge based on the .300 H&H case, trimmed. Ballistically, it was very close to the Ross, and both cartridges were loaded commercially in the U.S.. No rifles chambered for them were produced here, though.
A lot of shooters started shaping 7mm cases in the twenties and thirties. Some used Holland's belted brass, others the big rimless .30 Newton. Most of these designs remained wildcats, but Western Cartridge Company produced , briefly, John Dubiel's .276. An improved version of the .276 Dubiel was available from Griffin and Howe. The .288-diameter .280 Dubiel got no commercial support but performed impressively on its full-length .300 H&H case.
Charles Newton, at once among the most brilliant and unlucky of rifle designers, failed with his well-shaped .280. Much later P.O. Ackley had better success with his .276 Short Ackley Magnum. A.E. Mashburn also introduced a belted 7mm wildcat that skilled writer and marksman Warren Page used on hunts the world over.
That's a skeleton view of 7mm history. There's not room to cover the 23 domestic wildcat 7mms listed by Ackley, though some were and are interesting. The .285 OKH, for example, used a duplex powder charge ignited through a flash tube in the case; Wade's Super Seven was a blown-out .348 Winchester with the rim turned off. Through the 1940s and 1950s, only two commercial high-performance 7mm cartridges were available for shooters here.
Remington's big seven was first marketed in 1962, just five years after its own .280 was announced. But much earlier (in 1944) Roy Weatherby had designed a belted 7mm cartridge with even more muscle. An outstanding performer as loaded by Norma, it got limited play at market because for decades only Weatherby chambered it commercially. It is still one of the most useful of Weatherby's line.
Shortly after the war, Phil Sharpe and Dick Hart developed another belted 7mm. The Norma-loaded 7x61 Sharpe and Hart was chambered in the Danish Schultz & Larsen bolt rifle. It drove 160-grain bullets 3000 fps.
With so many people forming big 7mm cases, Remington wasn't really doing something new in 1962. But there's an advantage with an established arms company that promotes a product well. And the introduction at the same time of the Model 700 rifle gave the 7mm Magnum a nice boost. Here was a strong hunting rifle, much more attractive than the 721 and 722 but with their excellent trigger mechanism. The extractor was bigger, and you could get a hinged floorplate. While available in many chamberings, the Model 700 in 7mm Magnum became an instant hit. The cartridge shot as flat as a .270 but hit harder. It killed game like the .30 magnums but with less recoil.
Because the belted seven was almost immediately successful, a lot of what you read about Remington's magnum includes credits. Les Bowman apparently urged the development of the 7mm Magnum because he thought it would be a good deer and elk rifle for hunting his native Wyoming. He noted that hunters didn't shoot very well with big guns because they flinched. Reasoning that they wouldn't flinch as much if they weren't hit as hard, he advocated a smaller bore than .30, with bullets heavy enough to be effective on elk but light enough to be driven fast and cut recoil.
Remington engineers filled that order well. Factory-loaded 175-grain bullets are listed at 2860 fps, 150-grain bullets at 3110. A .30-06 drives its 180-grain softpoint 2700, its 150-grain 2910, while the .300 Winchester with the same 30-caliber bullets chronographs 2960 and 3290. Recoil of the 7mm is about 14 percent greater than that of a .30-06 when loaded with bullets of similar sectional density, but roughly that much less than the .300's. (Velocity figures are for comparison, valid because they're all from factory charts, about equally optimistic!)
The 7mm Remington has been one of those cartridges that seem to kill better than they should. Partly that's due to the bullets available for it. Remington's Core-Lokts have proven to be among the best for heavy thin-skinned game like elk, and while handloaders have dozens of bullet choices now, the first 7mm Magnum factory loads included Core-Lokts. What would the .280 Ross have done with such a payload?
Remington's rifle has also built a reputation for the 7mm. Strong, dependable, affordable and usually accurate right out of the box, the 700 is a standard for modern sporting rifles. Now you can get 7mm Remington Magnum guns of every description; but this widely-chambered round began life in the 700.
Handloaders can do a lot with this cartridge that they couldn’t before the availability of strong, accurate bullets and slow powders like 3100, 4350, 4831, RL-19, RL-22, 7828, and N-205. At 80 grains water capacity, the Remington case has room for coarse extruded powders and a relatively small bore to relieve pressure. So slow propellants are necessary for best results behind even 140-grain bullets,. Slow fuel is the only practical alternative in full-power loads with bullets of over 150 grains.
Because 7mm cartridges of several shapes are popular now, lots of 7mm bullets have become available. Some shooters regard this huge bullet selection a fine reason to buy a 7mm Remington Magnum instead of a cartridge with larger or smaller bore. Choice is good; still, you can shoot only one bullet at a time. Once you've found an appropriate bullet that will shoot well you don't need dozens of other styles .
Another myth to examine concerns ballistic coefficient. There's talk around now that 7mms are better because their bullets have high ballistics coefficients. In truth, ballistic coefficient is simply a mathematical way to express a projectile's ability to drill air. It can be determined by shooting or by a formula that includes sectional density and a form factor. Short bullets with blunt noses have low ballistic coefficients; long bullets with pointed noses have high ones. You can get bullets of high C values in most rifle cartridges, and you can get bullets of low C in most, too.
Sierra's 160-grain 7mm boattail bullet has a C of .561 --very high. But the company's 180-grain boattail in 30 caliber almost matches it at .534. Given the same starting speed, there's virtually no difference in downrange trajectory or retained velocity, even at distances far beyond normal hunting range. Hornady's sleek but short 120-grain 7mm Spire Point has a low C because it's short: .346. That firm's long but blunt 175¬grain bullet has an even lower one : .274.
Construction, weight and shape determine bullet performance in flight and in the game. For elk, heavy bullet jackets and devices to control expansion are in order. Penetration matters, which is why many hunters have relied on Nosler Partitions. Now you can choose from among may fine bullets designed for heavy game: Barnes Triple Shock, Federal Trophy Bonded, Hornady InterBond, Swift A-Frame and Scirocco , Remington Core-Lokt Ultra, and Winchester/ Nosler AccuBond.
This isn't to say bullets of conventional construction are inadequate. Regardless of design, you’re smart to stay with strong bullets reasonably heavy for the caliber when you're hunting elk. In Remington's 7mm Magnum, 160-grain bullets are a favorite with experienced hunters. Even a flat-base 160-grain spitzer will give you a ballistic coefficient of well over .400. Properly constructed, it will bore through lots of tissue and bone, killing your animal cleanly. Lighter bullets may leave the muzzle faster, but they lose energy faster too; for elk, bullets of at least 150 grains are best. The extra weight provides for better penetration and more delivered energy than is apparent on paper. While round-nose 175-grain bullets have the same advantages up close, they limit the effective range of your rifle. Remington's big seven has 400¬yard potential; you can tap that only with bullets designed to buck the atmosphere.
Most rifles chambered for the 7mm Remington Magnum have a twist of 1-9 to 1-9 1/2. Some of foreign make measure 1-10. All are fast enough to stabilize the heaviest bullets commonly available.
Pressures in the 7mm run to 54,000 psi. As with all belted cases, headspacing is on the belt and resizing should be limited to the neck if you're shooting just one rifle. That will greatly extend the life of your brass.
On its 25th anniversary, the 7mm Remington Magnum earned top billing in a popularity survey of 250 Rocky Mountain Elk Foundation members . Now, 20 years later, it remains a first pick for many. Among the most versatile of long-range big game cartridges, it has become a mainstay for deer and elk in the Mountain West.
. I've sure been called worse 
When I decide to build soemthing other than std I normally have a reason like burn less powder, get close without going to longer action, need a new discussion at camp or often just want to be different etc etc.
