i have a s&w mod 27( no mod # on crane) ser# S140629. this number is on the frame barrel, crane, cylinder even stenciled on the old grips (which i still have) stamped on the frame is a large R and the numbers 545 59. i am told this is not a register number because S number guns were not registered. so!! what does this number mean???? when was this gun mfg??