In the early 1930s, Bofors was hard at work developing a new AA weapon which became the famous 40 mm L/60 Model 1936 AA gun. The Swedish Navy was actively funding this project, but they were also interested in a smaller 20 or 25 mm gun. Firing trials with foreign guns were conducted in 1931, but none met the requirements laid down by the Navy. Later that year, the Navy approached Bofors again and Bofors obligingly designed a new 25 mm gun using the same operating scheme and autoloader design as the 40 mm gun, a decision which accelerated development. Both 25 mm and 40 mm guns were able to perform live firing tests against airborne targets during the summer of 1933. These were successful and in 1935 the Navy decided to procure both guns.
I lack enough information to build a complete datapage, but in general the 25 mm gun looked and performed similarly to the 40 mm gun and were produced in both single and twin mounts. Guns were used on at least the Tre Kronor class and Gotland class cruisers. Used a 25mm x 205R casing and had a MV of 2,790 fps (850 mps). Ammunition was supplied in six-round clips, similar to the four-round clips used for the larger 40 mm/60 guns.
Some of these 25 mm guns were exported to the Soviet Union in 1935 which proceeded to copy the design to produce their own 37 mm gun.
27 February 2018 - New Datapage