.345 Winchester Self-Loading

[1] It was designed by Frank F. Burton for the Winchester-Burton Machine Rifle, also known as the Winchester Model 1917.

[2] While few original documents pertaining to the rifle have survived, it was probably intended primarily for use as an anti-balloon weapon,[1] [3] while fitted to aircraft.

[4] These static balloons inflated with hydrogen, became targets for airmen on both sides, and were defended by anti-aircraft batteries and patrol fighters.

[6] In 1916, French officer Yves le Prieur created a rocket system powered by electricity, but its range was limited.

[1][5] To meet this need, Frank F. Burton of Winchester, developed the "Burton Light Machine Rifle", a selective fire blowback rifle, with selection of rate of fire to be used in observation and surveillance planes, the first practical version of which was ready in 1917.

The .345 Winchester Self-Loading cartridge.