Home Forums Hunting & Shooting Express Rifles and Big Bores Only The great 458 Winchester. Everyone should own one at least once

Sir John,
My experience is to expect about 20 fps more with another grain of AA-2230 added to your load of 75.0 grains with the 480-gr DGX.
You got 2198 fps instrumental.
If that was at 5 yards for chrono add 14 fps to correct to MV = 2212 fps.
If 2198 for MV by Lab Radar, no correction needed.

My load of 78.3 grains giving 2297 fps MV was in a 25" Shilen barrel instead of your 24" Whitworth barrel.
I got about 15 fps extra for my extra inch of barrel.
2297 -15 = 2282 fps for 78.3 grains AA-2230 expected in my rifle with barrel shortened 1 inch to 24".
3.3 gr X 20 fps/gr = 66 fps
2282 - 66 fps = 2216 fps for my rifle with 24" barrel and 75 grains AA-2230.
My MV 2216 fps for 24" barrel calculated.
Your MV 2212 fps for 24" barrel calculated.
Pretty darn close !

I predict you will get about 2232 fps MV with 76.0 grains of AA-2230.
Minus 14 fps for instrumental = 2218 fps.