My own goal is to produce safe hand loads that are comfortable to shoot from the bench for prolonged periods; will produce consistent, reasonably accurate, target groups; serve as suitable close range light game hunting loads. The near minimum (Hodgdon data) loads I am presently using in my CZ 550 American Magnum Safari .458 Lott rifle fall short of the "light game hunting suitability" criterion. I want to achieve approximately 1000 fps muzzle velocity with 500 grain bullets which will produce 1100 foot lbs of muzzle energy. I will work slowly to that end.
Early morning Range session -- very light breezes -- ideal for chronograph usage.
Hand loads using Hodgdon IMR "Trail Boss" powder; Hornady five times fired brass; HSM 405 grain lubricated, cast bullets (.458 diameter); Remington 9 1/2M magnum rifle primers; CZ 550 American Safari Magnum rifle - .458 Lott caliber.
Shooting from the bench under calm conditions - 70 F temperature - bright sunshine - Caldwell rifle rest. Bullet velocity measured using a ProChrono chronograph positioned 12 feet from the rifle barrel muzzle.
I opted for 405 grain bullets for better ballistic balance and cost savings. I loaded four groups of five cartridges (using Hodgdon IMR Trail Boss powder data) in 2 grain increments from a near minimum of 19 grains to a near maximum of 25 grains (I never use maximum loads as a matter of principle). Bullets were seated to the crimping groove but were not crimped -- I believed the very light recoil produced by these loadings would not result in bullet set-back in the box magazine -- this proved to be the case as rounds were chambered via the magazine (flawlessly), two and three, without any set-back.
Below:
HSM 405 grain lubricated cast lead bullet (top)
Fired Hornady cartridge case (middle)
Hornady 500 grain DGS factory jacketed bullet (bottom)
Showing relative OL lengths of bullets, seating position in case and location of crimping grooves (seated to this index)
I used magnum rifle primers to insure optimum powder burn -- fired cases were clean with no evidence of unburnt powder granules. The 19 grain (near minimum) loading produced the best target groupings and the most consistent velocities:
1165 fps
1157 fps
1160 fps
1169 fps
1169 fps
1164 fps average - 1157 low/1169 high
This average velocity with 405 grain bullets equates to 1219 ft/lbs energy (at 12 feet from the rifle muzzle). The oft quoted minimum striking energy for taking white tail deer and other thin-skinned animals is 1000 ft/lbs -- therefor I believe this loading meets my requirement for a suitable close range light game hunting load.
Caveat: My handloads work in my rifle. You may not achieve the same results in your rifle using the same load and components.
Always refer to the data published by Hodgdon relating to their IMR Trail Boss Reduced Loads For Rifle and Pistol prior to formulating your own handloads.
James
