The Bang rifle was a Danish prototype self-loading rifle.
The Bang rifle was designed in Denmark by Søren Bang and funded by the Dansk Rekylriffel Syndikat, a company that promoted Danish small arms internationally. It was initially developed in the late 1900s and chambered for 6.5×55mm Krag. The rifle was sent to Britain for testing by the Automatic Rifle Committee, where it was trialed in both 6.5×55mm and 7.65×54mm against other self-loading rifles. The ARC concluded that the Bang was one of the best designs of the rifles tested, and sent feedback to Mr. Bang, but ultimately no action was taken in regards to adopting the rifle.
In 1911, the rifle was submitted to the US War Department and tested at Springfield Armory. Like in Britain, the rifle received a positive reception, but there was no serious consideration for adopting the weapon. The rifle was further developed from 1919 onward and tested in various calibres, including the experimental .276 Pedersen cartridge. Trials for the Bang took place in 1927, and it was found to exhibit some faults, including overheating, corrosion, and stoppages. Development ceased in 1929.
The Bang was a gas-operated rifle which used a sliding muzzle cup system which was blown forward by the combustion gases while the bullet emerged from the barrel. The sliding muzzle cup pulled a piston connected to a rotating bolt, thereby unlocking it, and then pushed the bolt back upon reciprocating. The muzzle cup was susceptible to fouling, and therefore malfunction, due to the corrosive discharge of the bullet's priming compound.