English Proof Marks:
 

Looking at the Proof Marks on my recent A.J. Rudd acquisition. I believe it has both London and Birmingham proofs. I am suspicious that it may have been reproved twice. Hoping someone here can accurately decipher the story.

You picked up a really nice one there. Looks like original Birmingham 1896-1904 proof marks with a London 1954-1989 reproof. The LP over the two numbers should be the post 1972 London date mark. I can't make out the two numbers but I think those should be the year of the reproof. A Birmingham reproof mark would be a capital R under a crown while this has the stylized capital R under a crown from London. Others on this site know more than I though so I might be corrected.

The bore diameter stamps may indicate that the gun was not made with those bore diameters. I'm sure you have measured the wall thickness out of curiousity if nothing else.

It's my understanding the stamped measurements are taken 9" from the breech face. You are probably correct since the gun was re-proofed twice since the original proofing. The barrels have definitely been re-blackened due to their new condition and the bores shiny spotless appearance. The LP/89 stamp indicate re-proofing in 1989. Since it's unknown if any work was done after that your recommendation for a wall thickness analysis is good advice. I will certainly have the measurement done before use.
The bores looked clean when viewing but when I pushed the clean patch with "Hoppes" through the bores there was certainly evidence of black spent powder indicating the gun had been fired. Fired with what is an unknown. I wanted to contact the previous owner but the shop where I purchased it was reluctant to share the information.

The 20 marked on both barrels was the standard way they marked bore diameters at the first Birmingham proof. That would put them at .615" diameter at that time. Tf they were originally .626" it would have had 19 bore stamped there. Bores that are .010" over size compared to the original would put them out of proof. The .626" and .630" would mean both were out of proof which is why they had to do the reproof. Having the bore diameter marked in thousandth of an inch was standard in 1989. It looks like the barrels were cleaned up followed by a single second proof.

The chamber is still 2.5". An unfired 2-3/4" Federal will chamber, however a fired identical case will not. If the MWT is sufficient, the "Cheddite" 20 gauge 65mm or 67mm 2-1/2" case with a roll crimp and a low pressure 7/8 oz. load would be ideal.