When Czechoslovakia began looking for new small arms in the early 1920s, one of the things they were interested in was a "samostřil" - something akin to the automatic rifle in English. A select-fire weapon intended to be fired from the shoulder or hip - heavier than a basic rifle but lighter than a machine gun. This was a category of small arm briefly popular, and a few were adopted by different countries, with the most obvious being the US BAR (also the French Chauchat and the Russian Federov).

A Slovakian gunsmith by the name of Josef Netsch developed a self-loading system that he demonstrated to the Czechoslovakian military in December 1921 as a plain rifle, and was asked to submit in automatic rifle form. He received an order for 25 of these samostřil, and the competed in early 1923 for military contract against Hotchkiss and Krnka designs. His design was quite complex. It used a rotating bolt operated by a forward-moving gas trap system. Netsch lost out quickly, as his sample in the tests broke after just 23 rounds.

Ultimately, the "samostřil" type of weapon was scrapped by the military in favor of a light machine gun along the lines of what because typical. Neither of the other leading designs in that 1923 trial were adopted either, as continued development eventually led to the ZB26 by Vaclev Holek.

Thanks to the Czech Military History Institute (VHU) for graciously giving me access to this very cool piece to film for you! If you have the opportunity, don't miss seeing their museums in Prague:
https://www.vhu.cz/en/english-summary/