345 DeSoto
Member
What's about the limit on FPS for a cast (wheel weights) rifle bullet? At what velocity does barrel leading start to occur...all things being equal?
Wheelweight alloy ... bullet hardness ... generally comes out in the range of BHN of 10 to 12 for air-cooled bullets ... water quenching bullets cast of WW alloy produces a bullet with a BHN of about 18.
... At magnum handgun velocities (e.g. 1400 fps), bullets with a BHN of about 12 (e.g. air-cooled WW alloy) will expand somewhat. This is an excellent alloy for deer and black bear sized game. Water quenched WW alloy at BHN 16-18 is quite tough and will neither expand or shatter at these speeds. This is an excellent alloy for maximum penetration.
Leading caused by the bullet. The cause of leading can be traced to the bullet if it's the wrong hardness for the application ... too soft of a bullet (e.g. BHN < 8) can be stripped if pushed too fast, while a bullet that's too hard (e.g. BHN 22) can fail to obturate, and lead the trailing edge of the lands. The bullet can also be the source of leading if ... bullet in a load that generates more than about 40,000 psi peak pressure or 1500 fps muzzle velocity; these applications are better served by GC (gas check) bullet designs.
It just wouldn't be right to talk about cast bullets and buffalo and not talk about the .45-70, right? Rob used this combination, in the form of his Winchester 1886, to take a fine young meat bull a few years ago. His .45-70 loads were composed of the Lyman 457124 ... cast of air-cooled WW alloy (BHN of about 10-11), loaded over 50.0 grains of 4895, to produce a muzzle velocity of 1650 fps.
What's about the limit on FPS for a cast (wheel weights) rifle bullet? At what velocity does barrel leading start to occur...all things being equal?