From the introduction of the J. Stevens No. 530 in 1936 through the 1947 Savage/Stevens/Fox/Springfield catalogue the No. 530 is said to have a capped pistol grip. Beginning with the 1948 Savage/Stevens/Fox catalogue the Stevens Model 530 is just said to have a pistol grip. How closely what was being done on the factory floor coincides with what was stated in the catalogues is anyone's guess!! My gut feeling is the gun in question is of immediate post WW-II vintage.
There is no "Model 5100". The 5100 is an action type used on a number of Stevens, Springfield and trade brand guns. Through the 1920s and early 1930s, the bulk of the double barrel shotguns to leave the factory at Chicopee Falls, Mass., were built on the G.S. Lewis Patent No. 1,136,247, granted Apr. 20, 1915, action, which used coil-spring driven strikers rather than hammers which rotate about an axle -- the Riverside (later Springfield) No. 315 introduced just before WW-I, the Stevens No. 330 introduced about 1923, and the Springfield No. 311 introduced in 1929, as well as hundreds of different "trade branded" guns.
The first appearance of the "5100" action I see in J. Stevens Arms Co. paper is when the new No. 530 replaced the old G.S. Lewis auctioned No. 330, in 1936. In 1940, the J. Stevens Arms Co. introduced a Tenite stocked version of their Stevens No. 530 double with the 5100 action, as the No. 530-M.
After WW-II, Savage Arms Corp. consolidated their arms making operations at their Stevens factories in Chicopee Falls, Mass. The same gun as the pre-War Stevens No. 530-M was shown as a Springfield No. 311 in the 1947 Savage/Stevens/Fox/Springfield catalogue.
By the 1948 Savage/Stevens/Fox catalogue the Springfield name was gone and the same gun was listed as a Stevens Model 311.
By the 1951 Savage/Stevens/Fox catalogue the Tenite stocks were gone and the Stevens Model 311 had a wood stock and forearm. The walnut stocked Stevens No. 530 with the "5100" type action remained in the line through 1953.
