All the info I have is from 1979, and not for the later versions. The L29A1 used NQ/M and was obsolescent. The L29A2 used FNH and was obsolete. I have no info for the L29A3 (at least obsolescent by 1979), L29A5 and L29A6. I can only assume that the L29A4 was already obsolete or was not proceeded with, as my notes say there were only five model numbers at that time.