Thanx for the responses. 2.830 is the measurement of my chamber using the Hornady guage. Seating the bullet to 2.810 (-.020) puts very little of the bullet into the case mouth. I may be overthinking this. I understood bearing surface to mean how far the bullet seated into the case. No? Out of curiosity I measured a Federal 180 gn and got 2.105. That's a heck of a jump! Anyway, gonna go with COL for the time being.