This is a British Molins No. 2 Mrk. 5 flare gun, built by the I. L. Berridge & Co. during WWII. About 200,000 thousand were made. The flare gun was also called a Very Pistol which was named after the inventor of the flare gun Lieutenant Edward W. Very. Flare guns were heavily used in both world wars by all sides. This flare gun of World War II had a 1 inch bore or 25.4 mm.