I assume you checked the bearing surfaces for wear and they looked even and smooth as stated. Was the previous BB the same type of assembly or sealed? What I am getting at is the possiblity of the need to face the BB. The other issue, which you may be fully aware of, is how you tighten the lock ring. This is just like cup and cone on wheel hubs and head sets. Once you tighten the lock nut, the distance changes to either too loose or too tight. If you already know and have experience with this, read the next posting!