The Remington Model 8 was one of the first successful self-loading rifles introduced to the commercial market, and it was designed by none other than John Browning. It was an expensive rifle, but popular for its power and reliability. In the 1920s, an entrepreneur founded the Peace Officer Equipment Company to sell police gear in St Joseph, Missouri. He would design a conversion to the Remington Model 8 to replace its fixed 5-round magazine with larger detachable magazines (5-, 10-, and 15-round, with 15-round being the most common by far).
POEC made and sold the conversion until about 1936, when Remington replaced the Model 8 with the slightly improved Model 81. At that point, Remington licensed the magazine conversion themselves, and offered it as a factory option, under the Special Police name. Remington had big hopes for the rifle, but only a few hundred were sold, with the LA County Sheriff being the single largest customer, ordering 200 of them. This rifle is one of the LA guns, number 40 of their order.
Remington Model 8 in .25 Remington: https://www.full30.com/video/13821a6b49b15fbd080eb581b14bd7fe
Remington 8 in Slow Motion: https://www.full30.com/video/7180747655f844b9b88d994801b6a848
History of Police Armament: https://www.full30.com/video/91af5cf47cbccba05a217f497acb99ea
High Standard Model 10B: https://www.full30.com/video/5790be65e9d2024cf33243ea9225b62b