Over thousands of rounds, I think chrome lined holds up better. I have around 5500 rounds or so on one of my rifles, and still shoot 1-1.1MOA 10-shot groups at 100 with it using a NF 1-4 scope. 2000 of those rounds were wolf bi-metal jacketed junk ammo at a Nightfighter course. Weapon has seen several carbine courses, run smoking hard on occasion. Still does the deed when I plop down at a bench and shoot for groups.