The Praga I was the first machine gun design from noted Czech arms designed Vaclav Holek. Three examples were made for Czech military testing in 1922, but they were not acceptable. Instead, this design served as the first stepping stone to the eventual development of the ZB-26, perhaps the best of the interwar light machine guns.

Mechanically, the Praga I is largely based on the Vickers/Maxim system except with a locking wedge instead of a toggle joint. It also uses a forward-moving gas trap sort of action instead of recoil operation like the Maxim/Vickers. The fire control mechanism is essentially a Vickers lock, just built into the receiver of the gun instead of in a moving bolt or lock. It is a truly fascinating system!

Many thanks to the VHU - the Czech Military History Institute - for giving me access to this fantastic prototype to film for you. The Army Museum Žižkov is a part of the Institute, and they have a 3-story museum full of cool exhibits open to the public in Prague. If you have a chance to visit, it's definitely worth the time! You can find all of their details (including their aviation and armor museums) here:

https://www.vhu.cz/en/english-summary/