"My COAL looks like the SAAMI Max of 3.340” for the unaltered M70 458 Winchester."
R: Are you sure? I just this minute slipped a 3.380" COL into the box of my unaltered M70 .458 Winchester Magnum Super Grade. My box is a little over 3.4" inside length. Most I have measured are about 3.42". Additionally I can single-load the 3.480" COL dummy and eject it after chambering.
"So my velocity hopes out of the 22” barrel, shall be lower than your lowest achievement. I will be satisfied with 2300 fps. Anything over 2300 more happy."
R: Maybe. But you do get more bang per grain of powder in a shorter COL. Cartridge Overall Length is your friend, short or long. The latest test with differing COL and all else same: 3.380" COL gave 2489 fps MV 3.480" COL gave 2425 fps MV Shortening COL by 0.100" gave 64 fps more velocity. That alone could compensate for about 3" of barrel shortening in the 20" to 24" length range. Shortening COL to 3.280" will get velocity even higher for same powder charge and barrel length. Just work up for velocity/pressure for your rifle with COL you prefer, as you please, looking for accuracy nodes.
Velocity for barrel length varies greatly among rifles. Tim Sundles has an 18" barrel and a 22" barrel that both produce about 2250 fps with his 400-gr TSX load for .458 WinMag, 22" velocity was 2247 fps. 18" velocity was 2250 fps, quoting his web site. His COL is 3.310" for the commercial load. Same load in my 24" Ruger No. 1 gave 2325 fps at 5 yards, 2338 fps MV for G1 BC = 0.324 so you never know until you try.
"At 2300, based on a BC of .410, I should still be slightly about 1900 fps at 200 yds with minimal trajectory concern."
R: Count those chickens after they are hatched. I am hoping to shed some light on the G1 BC estimate of 0.419 with some shooting at 100, 200, 300 and 600 yards.
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.
