Thank you. So if the Speer manual is correct, the 375 Ruger/ 416 Ruger brass should have a slight more capacity in equal calibers.
Yes, both by calculation and actual measurement, the 375 Ruger case has significantly more capacity than the 458 WM case. I routinely load 83-85 grains of extruded powders in the 375 Ruger or in my wildcat 404-375 Ruger with monolithic solids - which are long for weight - or Barnes TSXs . No significant powder compression is needed to load these bullets and stay withing the COAL required in the MKII/Hawkeye magazines of 3.390-3.40".
Getting that much powder into the 458 WM case and then seating a 450 grain monolithic solid requires significant compression, unless you stick to spherical powders, like AA-2230. I was able to load 80 grains of 2230 behind a CEB BBW#13 today at COAL = 3.390" without trouble but the same charge with Varget required significant compression with the same bullet.
True, all that. The RCBS Cartridge Creator algorithm shows .416 Ruger = 101.5 gr water .458/.416 Ruger = 104.2 gr water That is for a simple necking up of the .416 Ruger and keeping max brass length at 2.580" for both.
My fire-formed .458/.416 Ruger brass comes out 2.565" in length. Measured case capacity for that average is 104.47 grains water. Correcting to 2.580" max brass length gives 105.1 gr water.
Mine is a .458 Win Ruger and can be loaded to same long COL as the .458 WM+, which is a longer COL than the SAAMI .458 Lott can handle.
Ron aka "Rip" for Riflecrank Internationale Permanente NRA Life Benefactor and Beneficiary .458 Winchester Magnum, Magnanimous in Victory THE WALKING DEAD does so remind me of Democrap voters. Donkeypox.
