I am casting a bunch of 230 grain round nose bullets to me shot in three different Kimber 1911�s. What size die should they be lubed and resized in, .451 or .452?
There is no way to predict which diameter, .451 or .452 inch, will work better. Each pistol will tell you what it prefers, though you may need a Ransom Rest and a large number of groups to get a reliable answer.
