Cartridge: 500 Linebaugh
Firearm: Converted Ruger Blackhawk, 7.5″ Mag-na-ported Barrel
Powder: Trail Boss 2.2cc Lee dipper ≈ 9.4grains ± 0.2
Bullet: 420gr Hunter’s Supply
Primer: Winchester WLP
LabRadar series: 81
Shooting Record: 5 shots, 4/11/2017 @ Sunnyvale Rod & Gun, between 8 and 9 PM
Velocity: 768 fps
Spread: 778.6 – 757.4 = 21 fps
Drag Coefficient: -0.56 fps/yard over first 60 yards
Notes: Recoil was very controllable, no pain at all, I could make 100 yard hits repeatably. Winchester WLP primer helps identify light loads.
Although very slow, 420 grains × 768 feet per second = 240 grains × 1,344 feet per second, which approximates 44 magnum factory ammunition. And there was much less muzzle blast than with a 44 magnum. I was fortunate enough to be able to setup my chronograph at the 100 yard steel, and the LabRadar indicates that velocity-loss was pretty good for a pistol order of 1 fps lost for 6 feet of travel.
I only got data to 60 yards. But extrapolating to 100 yards, the slug would still be moving at about 710fps — still a “Power Factor” of ~300.