P33RR1342 indicate's a 1977(RR) manufacture of a 20 gauge Lightning(33), Presentation Grade(P), 1342 of that year.
The serial # will not tell you the actual Presentation Grade and pictures and references are needed or contact the Browning Historian(Glen Jenson).
Presentation Grade Superposed started in 1977 and were a way for Browning to control prices as many are a combination of engraving and acid etching. Many of the engravers refused to sign thier work on these Grades. When first offered, you couldn't give them away. Now the stigma seems to have been lost with time and values are climbing.
Even if the P Grade was known without detailed condition even an estimate is not accurate.
The other 12 gauge is an early gun and appears fairly standard. Again condition is everything.
Ned Schwing's book 'The Browning Superposed' is a good starting point but Glen should be able to research the # and give you the grade easier.-Dick

Last edited by Dick_dup1; 10/25/09 09:35 AM.