Holy Cow, never on a lever or straightwalled case. Lots of things you can check. Did you trim your brass? Is bullet loaded COL longer than SAAMI specs?

Perform the split case technique. Find out where the bullet hits the rifling. Are you crimping. Are you belling too much. Goodness, that a first for me.

I have a older 700 in 7mm08 that you have to seat real deep. Alot of factory loads are too long. But I like it that way myself. It shoots awesome. But its rare to see levers like that.