All was quiet for about 15 years until Remington introduced the 8mm Remington Magnum. Simply a necked-down and improved .375 H&H, its claim to fame was that it was later wildcatted into the 7mm Shooting Times Westerner that eventually became a factory loading. The .416 Remington Magnum and, shortly thereafter, the even-hotter .416 Weatherby Magnum ended the renewed magnum cartridge competition for a while. Every one of these has a belted case.
Unless you've been asleep for the past few years, you've surely heard about Remington's Ultra Mag and Short Action Ultra Mag, and Winchester's Short and Super Short Magnum cartridges. A common feature of these recent magnum-rifle cartridges is that their cases are not belted. They are all loosely based on reworking the .404 Jeffery case. Apparently, the H&H design legacy has been interrupted.
I've spent some time tracing the history of belted and beltless magnum cartridges because they have continued to play an important role in the development and evolution of new firearms and munitions. Bear with me just a little longer and read about an obscure arms and cartridge designer who--at about the same time that the .375 H&H debuted--designed a cartridge with the most distinct features of the new .375 Ruger.
A century ago, Charles Newton was first recognized when he developed a couple of high-performance cartridges for Savage. The .22 Hi-Power and .250 Savage were the first to achieve the magical 3000 fps performance level. Both loadings were popular then, and they are still chambered in a few European and American rifles. Newton recognized that he could achieve even greater performance by necking the .30-06 case down to launch lighter bullets at maximum velocities. The .256 Newton was actually the precursor of the .25-, 6.5-, and .270-caliber adaptations of the .30-06. Newton soon started his own rifle company, and he went on to design additional cartridges.
The .375 Ruger's case capacity is about six percent more than the .375 H&H.
After the success of the .256 round, he developed a larger-capacity .30-caliber rimless cartridge. The .30 Newton's rim/case head diameter was essentially the same as the .375 H&H, but Newton's was beltless. His new cartridge had the same overall length as the .30-06, so it readily fit the standard long-action magazine.
Later, Newton necked up his .30-caliber creation to form the .35 Newton case. Some references list phenomenal yet somewhat questionable ballistics--.250-grain bullets at more than 2900 fps. Unfortunately, he tried to introduce his new rifle and cartridges at a most inopportune time. The world was engulfed in World War I. And to add to his misfortune, DuPont's improved military rifle (IMR) propellants, which would have ensured outstanding performance from his overbore rounds, didn't come along until several years later.
Because no published load exists for the new .375 Ruger, Lane used a Powley Calculator to determine which and how much propellant to use for his handloads.
However, the 1948 supplement to Phil Sharpe's Complete Guide to Handloading relates an interesting story. In the late 1930s, handloader Vernor Gipson necked up the .35 Newton case to .375 caliber and chambered a custom Enfield rifle for his wildcat. Sharpe stated, "With any .375 bullets and 4350 powder, this .375 Gipson-Newton appears to be equal to, if not better than, the .375 H&H."
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