RobD & JOG,
This thread got my curiousity up and I had to look at my BL-22's. Both of mine follow the Browning link. The first made in 1983 is XXXXXPX226 and the second made in 1990 is XXXXXNM226. I looked at other Browning serialization schemes to see if anything matched RobD's and came up empty handed. Interesting isn't it. Maybe an expert in Brownings will step in and help you out. The BL-22 is a neat little rifle isn't it?