Over the last 15 years I have fallen in love with the cartridges in the 7mm family. Working with, and modified multiple 7s including the 7mm RUM, 7mm Rem Mag, 7mm – 08, 7mm WSM, 7mm LRM, and the 28 Nosler, each has taught me something new as I struggled to find the optimum neck size, freebore and load for best accuracy and performance. I found that each had some value or purpose, except maybe the 7mm RUM that, without a muzzle brake, seemed to violate every part of me when I pulled the trigger.
With the end of my physical ability to hunt, I will be switching over to benchrest competition to feed my need for reloading, testing loads, bullets, powder, and shooting sports. Before do so, I wanted to build one more long-range hunting rifle. This one will be used occasionally, while taking advantage of handicap mobility privileges, for Antelope hunting. The rifle will be a 7mm wildcat that provides more than the 7mm Remington mag, 7mm PRC and 7mm WSM, but less than the 7mm RUM and 28 Nosler.
Care to guess what is? I have dubbed it temporarily as the 7mm Nosler Short Mag (NSM). Here is how it compares visually to some of the other 7mm 404 Jeffery based cases that I have worked with:
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Basically, the 7mm NSM is the 28 Nosler case shortened to 2.35". It retains the neck length and shoulder angle of the 28 Nosler. The new case is close to the 7mm Blaser Mag developed in Sweden. Like the Nosler and Ultra Mag cartridges, the 7mm Blaser Mag cartridge is based on the 404 Jefferies case. The primary difference between the 7mm Blaser Magnum and 7mm Nosler Short Magnum's Body Taper and Shoulder angle. The angle on the Blaser is 30 degrees while the 7mm Nosler Short Magnum is 35 degrees. This 7mm NSM case also uses the neck diameter and Freebore of the 7mm PRC. This altered case has about 4-5 more grains of H2O compared to the 7mm Blaser Mag.
My challenge now is to validate third party load data for the 7mm Blaser Mag or to show the 7mm NSM can meet or exceed them. The Chamber drawing in QuickDesign seems to be right, but I need help with the Gordon Cartridge Designer. I have attached the Gordon drawing and data fore review.
Note on the Gordon Chamber drawing the "S" Dimension has a problem. I assumed incorrectly what is was. Can someone help me with it?
I thought it was the dimension from the base of the case to the base or start of the body. Thoughts?
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