I had my heart set on a RRA 2-stage ($120), then while digging, I stumbled across the CMMG ($139). The CMMG has set screws for over travel and takeup. Neat, I guess, but the CMMG has brass pin bushings. OK, I can see where that might aid in the smoothness dept. But, with brass being softer than steel- what is the likelihood that tolerances will increase to the point of annoyance due to wear of the brass? I've seen brass used in industrial mechanical settings (friction plates, etc) to satisfactory results. Would anybody choose one over the other? Why?