.475 Linebaugh (using Hornady bullets)
Date: Mar 29 2016
In 1985 John Linebaugh developed the .500 Linebaugh cartridge using .348 Winchester cases cut to 1.400 inches and stoked with .510- to .512-inch bullets. Guns were custom built and were usually based on the Ruger New Model Blackhawk (Bisley Model) converted with a specialized five shot cylinder. Brass soon became difficult to obtain, however, so John began experimenting with the .45-70 case, likewise cutting it down to 1.400 inches and loading it with .475-inch bullets, and thus the .475 Linebaugh was born. It remained a "wildcat" until 1998, when Buffalo Bore Ammunition began offering factory loads. These loads were distinctly different than the original Linebaugh version, however. First, the rim diameter was reduced from .608 inch to .540 inch to permit it to fit in the compact cylinder diameter of the Freedom Arms Model 83/757. Second, the bullet nose was shortened to .360 inch to shorten overall cartridge length, a modification that allowed its use in the comparatively short cylinder of the Freedom Arms revolvers. Finally, the case was thickened to increase strength and durability. Freedom Arms almost immediately began chambering guns and the cartridge was soon introduced as a standard industry cartridge. The .475 Linebaugh is a superb hunting cartridge that has taken all of the world’s largest and most dangerous game.
To keep bullets in place and prevent their "walking" out the cylinder when subjected to heavy recoil, a maximum crimp should be applied. Case-to-bullet fit should also be tight, with the expander ball measuring .006 inch smaller than bullet diameter for additional bullet pull. Bullets should be seated to the correct overall cartridge length, then a roll crimp applied as a separate step.
Starline Brass and Buffalo Bore Ammunition offer cases that will handle maximum pressure loads of 50,000 psi (with all loads herein being well under that pressure limit).
Start loads should not be reduced, or hang-fires and erratic pressures may occur. Each of the powders used to develop the accompanying data delivered excellent accuracy in the Freedom Arms Model 757 .475 Linebaugh.