At what muzzle velocity can you drive a cast bullet to before it requires a gas check to prevent leading?
I'm looking for a general rule, if there is one.
I'm sure the condition of the rifles bore would play a major roll as to whether or not it could exceed the rule or required a gas check before the rule threshold is reached.
Of course bullet fit to the bore is vital too.
I am driving a 250 gr. Lyman 452664 bullet cast with 20:1 alloy to about 1240fps.
I do get a little leading that is easily removed during regular cleaning without too much effort.
The bullet is lubed with homemade Emmerts Improved and sized to .452" in a Redding lubricant-sizer. Miroku/Winchester M73 45 Colt 24 inch barrel.