Q: About twenty years ago I owned a Remington Model 700 in 7mm Rem. Mag. that I reloaded using Norma brass and AR2209 and H4831 powders. My best loads were: 140gn Nosler Partition and 68gn of AR2209 for 3140fps, the 160gn Sierra and 70gn of H4831 for 3020fps, and 175gn Speer and 70gn of H4831 for 2985fps. I sold that rifle in 1993 and only recently bought a new Ruger M77 Mk II in 7mm Rem. Mag. Planning on reloading for the new rifle, I bought a Speer Reloading Manual and the suggested maximum loads surprised me. Speer lists 63gn AR2209 with the 145gn bullet, 62gn of AR2213sc with the 160gn and 60gn with the 175gn. They listed the same Maximum Cartridge Length of 3.290″ that I used. I’ve been told that AR2213sc has an identical burning rate to the old H4831, but Speer charges are way below what I used to load. I would appreciate your comments as the throat for my old rifle was not free-bored.
A: For a start, the loads in the Speer Manual were developed in a test barrel fitted to a universal receiver, not a sporting rifle. But loading data for the 7mm Rem. Mag. varies widely with Hodgdon’s maximum loads being lower than those of Speer and Hornady’s different again. This is very confusing for the beginner, but I’ve found that different makes of 7mm Rem. Mag. cases vary a lot in weight and thus capacity with Norma holding 10 grains of powder more than the case with the least powder space. I mentioned all this in a previous reloading column. The powder charges I loaded for A Remington Model 700 in 7mm Rem.Mag. were almost identical to yours, but bear in mind that we were using the old H4831 and not the new stuff or AR2213sc. Speer used Remington-Peters brass to develop their data not Norma brass which makes a difference. My old Mauser would digest loads that would be dangerous in any other rifle, 10 grains over the listed maximum for H4831 in one instance. So I would recommend caution when reloading for your new rifle. Consult your manual and work up from the starting loads.