Example: I am crimping my Lyman 452664 cast RNFP bevel base bullet.
This bullet has a classic deep groove and a 45 degree slope down out to the bullet side.
Where should the case mouth be in relation to the crimp groove to start the crimp?
I have been seating the bullet so the case mouth is even with the lower edge of the top drive band which puts the deepest part of the crimp groove flush with the case mouth.
Usually the case mouth clips the sharp upper edge of the crimp groove as it roll under this edge.
Should I be leaving a few thousands of and inch clearance for the case mouth to be rolled under so it doesn't clip the crimp groove edge?
On my last crimp session I took note of my COL before and after crimping and found the COL shortened by approximately 5 thou.
I didn’t think I was over crimping just trying to get the case mouth under the edge of the crimp groove to prevent the bullets from being pushed deeper in a tube magazine.
Redding die set was used.
I have no problem crimping bullets with a cannelure, I crimp to leave one forth of the nurling of the cannelure exposed.