The proofs are under the 1891 -1938 proof laws. In 1939 the nazi's changed and added new proof regulations. I can't see the proof clearly but I believe dougk is correct in assuming the date is 1927. However, I am suprised at the hammers on a gun this late. It was certainly a special order so the customer could have what he wanted. dates coded such as ?/27 are more frequently found on Suhl proofs. I don't believe dating was required under the laws at the time. Many only have a number indicating the number of the firearm submitted for proof that year. The Rifle barrel is Nitro proofed for an 8 gram (123 grains) KMG bullet i.e. Kupfer Mantel Geschoss, copper jacketed bullet. The sights are likely regulated to this weight bullet and anything lighter or heavier probably won't shoot to the sights. The shot barrels are the normal '91-'39 proofs. the crown over W, indicates choke boring and the crown over S, designates shotgun/smooth bore proof. the 13/1 under the 12 in a circle indicates the actual proof bore standard that it was proofed under. At this time some standardization regarding shotgun bore with other countries was in place, Britain Belgium..The bores would have been 18.26mm slightly smaller than a true 12 at 18.52mm . The German's, unlike the British did not normally proof for a specific shot charge. It would be unlikely that the load for the short (65mm or shorter)shells would have exceeded 1 1/8 oz. If you 'mike' the bores I'm sure you will find them undersized (assuming they have not been polished out) Since there is no chamber length indicated assume the chambers are 65mm or shorter!! The other proofs mostly indicate acceptance (provisional proof,crown over U w/ eagle). I'm trying to do this from memory as I don't have the pics up in front of me. I'll edit this if I've missed something. The fully spelled word Nitro was required after 1912 as was the cal. i.e. 6.5mm over 52. Other pics might help. The "S" on the rifle barrel with an indestinct mar on either side(one loocks like crossed swords or keys, is Simpson's identifier.
I love hammer guns and those cool peninsular locks are really neat.
