Are you chamfering case necks? That should reduce amt. of pressure needed to start bullets.
Mark caused by seating plug not fitting ogive of bullet used. Won't hurt anything, but you could probably get rid of it by using a bit of valve grinding compound on a bullet and spinning w/drill (if bullets long enough to chuck, or by hand if not). could also use a steel ball bearing of proper size. Won't take much to remove sharp edge on seating plug.
Regards,
hm