I agree that your die is a little longer than your chamber, and excessive cam-over won't help. You can either lap (emery paper on a glass surface) a shellholder or shorten your die. Shortening the die requires a machinist who has a tool-post grinder for his lathe. I suggest that you contact RCBS; they may do the work gratis. I wouldn't buy any more dies unless you particularly want those dies.
Cam-over just abuses your press; once the die and shellholder are in full contact, no further sizing is being performed. The Redding presses have stops built in to prevent actually going over center.