Headspace-Operated Prototype Rifle - Yeah, it's as Weird as it Sounds

The H&K XM-8 was a significant contender to replace the M4/M16, featuring a modular design with multiple barrel lengths and an integrated optic with laser/illuminator. Its AR-180 style gas system and polymer construction with a metal trunnion offered a modern approach. The rifle boasted ambidextrous controls and a unique paddle magazine release, showcasing advanced ergonomics for its time.

The AK Fm/57 was a Swedish paratrooper prototype rifle developed in the late 1950s, based on the Ljungman AG-42 but modernized with a short-stroke gas piston and folding stock. Despite being chambered in 6.5x55mm, it was designed for the eventual 7.62 NATO transition. It competed in trials against foreign designs like the G3 and FAL but was ultimately unsuccessful, with the G3 being adopted as the AK4.

The Kholodovskii Mosin Nagant was an ambitious prototype aiming to improve the standard M91 rifle after the Russo-Japanese War. It featured significant weight reduction through aluminum components and barrel fluting, along with ergonomic and sight enhancements. Despite its innovative design, it failed field tests due to high production costs and poor performance, ultimately being scrapped in favor of simpler models.

The Johnson Model R prototype, developed by Melvin Johnson, showcases an early iteration of his semi-automatic rifle design, featuring a unique rotary magazine to address reliability issues encountered in trials. Despite its innovative short-recoil action and attempts to meet military bayonet requirements with a reciprocating handguard, the Model R ultimately failed to secure a military contract, paving the way for the later M1941 Johnson rifle.

The Hagen Prototype Semiauto Rifle, designed by Hagen and manufactured in the UK, was tested by the French military in 1912. It features a proprietary 7x56.5mm cartridge, a long-stroke gas piston, and a two-lug rotating bolt. Despite good accuracy and trigger, French trials revealed significant reliability issues, including 22 failures to feed and one to eject in 200 rounds, culminating in a broken gas piston.

The Samostril Netsch was a bizarre early 1920s Czech prototype automatic rifle designed by Jozef Netsch. It featured a unique gas trap system where a forward-moving barrel shroud cycled the action. Intended as a rifle-machine gun intermediate, it competed in 1923 military trials but failed after limited firing. Despite its failure, 25 were contracted, with many surviving in the VHU Prague collection.

This video details the unique 'French Finger Trap' issue with the MAS-36 rifle's bayonet, where two rifles can become unintentionally locked together. A 1951 French arsenal memorandum identified this problem, proposing a simple modification to the bayonet handle. Drilling a small hole allows a tool, like a firing pin, to depress the internal spring, enabling the separation of locked rifles.

The M134 Minigun is a scaled-down 7.62 NATO rotary cannon, requiring 24V DC power and consuming 1.5 kW. Its high rate of fire (3,000+ RPM) is essential for aircraft engagement windows. The complex delinker mechanism is critical for feeding ammunition, and practical hand-held use is impossible due to weight and recoil. Live fire demonstrates rapid ammunition consumption and the need for indirect aiming.

The H&K G11 is a revolutionary prototype assault rifle designed in the late 20th century, notable for its caseless ammunition and unique rotating drum bolt mechanism. Despite advanced features like a 2000 RPM burst fire rate and integrated optics, its development was ultimately halted by geopolitical shifts and cost concerns.

This video demonstrates the assembly and live-fire of the German 1936 pattern light mortar (L.Gr.W.36). It highlights the mortar's leveling mechanism for accuracy and the difficulty in visually tracking its 50mm projectiles after firing. The content showcases historical military hardware and its operational use.