I have found that all my rifles like to be .030-.050 off the lands, I got pretty bad groups any closer. Like mentioned already, at least a caliber deep, that's my starting point. I've experimented with crimp vs no crimp and some shot better, some didn't, but not enough to worry about. I only crimp for my 30-30, I just don't like working the brass any more than I have too.
I've also done the crimp with at cannulure vs crimping with no cannelure and could not tell any difference. The seating depth had a greater effect on accuracy than if it was crimped at a cannelure or not. So I'd crimp if it makes you feel better, but I'd find a seating depth that works for you, than try checking to see if crimping makes a difference. Some guys will tell you not to crimp without a cannelure because it "deforms" the bullet, but what is a cannelure? A deformation in the bullet
, it's just done by you at the bench and not at the factory.