The .28 Nosler is a shortened version of the 7mm Remington Ultra Mag. They share a maximum body diameter of 0.550 inch. Rebating the rim to 0.534 inch simplifies the production of rifle bolts since the rims of Holland & Holland-style belted magnums, such as the 7mm Remington and .300 Winchester, are the same diameter. Whereas the 7mm RUM case measures 2.387 inches long from head to body-shoulder juncture, that dimension on the .28 Nosler case is 2.166 inches.
The dimension at that point on the Nosler case is 0.002 inch larger and that reduces its body taper by just a tad. Maximum case lengths are 2.850 and 2.590 inches respectively. Shoulder angles are 30 degrees for the Remington cartridge and a slightly sharper 35 degrees for the Nosler. Due to its greater length, the Remington case is about 25 percent more capacious than the Nosler case.
The .28 Nosler case can be formed by running 7mm RUM or .300 RUM cases through a .28 Nosler full-length resizing die with its expander/decap assembly removed and then trimming to the proper length. But despite the best of efforts, case loss will be high due to wrinkling.
A case-forming die is available from Redding, and while I have not tried it, another Redding die on my shelf forms the 6.5 Remington Magnum and .350 Remington Magnum cases from the longer 7mm Remington Magnum case. Case loss is zero with it.
The 7LRM (Long Range Magnum) is a non-belted case that has the same overall length as the 7mm Rem Mag with a standard magnum case head. However, the body diameter is larger with no belt. The case neck is longer and the shoulder angle is 30 degrees. The case will fit and feed from a standard magazine box. Velocity with a 180 grain bullet is 3075 to 3100 fps from a 26-inch barrel length. See below for a comparison of different 7mm cases.
The brass dimensions and tolerances are outlined in Figure 2. Gunwerks has a very nice no-turn-neck, piloted reamer available to do custom barreling on your action—or start from scratch and have us build a full custom rifle. This is not a standard SAMMI cartridge; it is important to use a reamer with correct dimensions and clearances to ensure best accuracy, and longest brass life.
We needed to balance the requirement of a minimum-velocity threshold of 2000 fps at 1000 yards with a hunting weight bullet, and wind deflection numbers that will allow 30- 50% uncertainty in our wind estimation against recoil, cost, and case life for reloading. We wanted a cartridge of modern design that fit in a standard magazine box and would take any game we wanted to chase in all conditions— basically, the ultimate hunting cartridge.
First off, we settled on the 7mm diameter bullet because of the high ballistic coefficients of hunting-weight bullets from 160 to 180+ grains. Then we looked for a case to base the cartridge from, saving thousands in tooling costs. The 375 Ruger from Hornady was perfect. The 375 is very similar to the genius 30 Newton cartridge from 100 years ago. This cartridge case fits a standard magnum bolt face without modification, and there is no rebated rim as on the massive Ultra Magnum case. We fit the neck length to the longer 180 grain bullet, with the overall case length of 2.5 inches. With a 30-degree shoulder and minimum body taper, we achieve nearly 3100 fps velocity with a 180 grain bullet. If one compares the LRM case against two of our other favorite cartridges (the 6XC and 6.5-284 Norma) you will notice some striking similarity.
