How to choose the right cast bullet

Hi! I'm trying to reload cast bullet ammo formy old , last, No.4. It's well worn and i'm going to reload cast bullet for him. How could slug the bore and throat?
I used old trick : a fishing plumb on yhe muzzle forced with a wood dowel to the chamber and measured it... Now i do not remeber exact results but what i shalll consider ?? Diameter between land or diameter between grooves ( that is bigger)?

And...last but not least how could i bore the throat?

Always the groove diameter. You want a bullet 1-2 thousandths larger. Best weight is going to be in the 200-220 grain range. I'd suggest a Lyman 314299 as a good place to start. Why do you want to bore the throat?

Bow,

Open this link and read the article--http://www.303british.com/id37.html

All the best--

Curator
Member of "Rule 303"