The video presents a top five list of experimental guns drawn from different eras of firearm development. The focus is on designs that pushed beyond conventional service rifles and compact automatic weapons, especially from the 1990s and early 2000s, when many ambitious projects appeared but never reached widespread adoption. The host explains that every service weapon begins as an experiment, but this list highlights firearms that significantly broke with traditional operation, layout, or ammunition concepts. Some of these designs later influenced successful platforms, while others remained prototypes or curiosities. The countdown moves from more obscure or niche experiments toward a number one pick that came close to replacing a major service rifle, with attention to how each project performed in testing, how it was received, and why it ultimately stayed experimental.
The first firearm discussed is the XM29, a large, bullpup experimental weapon system sometimes referred to as a SABR, or selectable assault battle rifle. It combined a 5.56mm rifle with a 20mm airburst high-explosive grenade launcher in a single, bulky package. The XM29 did not fit neatly into existing categories, which led to improvised terminology and highlighted how unconventional the concept was. Heckler & Koch contributed to the project, and its futuristic appearance invites comparison to other HK experiments like the G11. The XM29 was fielded in limited capacities but proved overly complex and cumbersome. Eventually, the XM8 program superseded it, and the combined 5.56 and 20mm airburst concept did not move forward into general service. The XM29 remains better known today through appearances in older Call of Duty titles than as an issued weapon.
The next firearm is the Lebman machine pistol, a heavily modified 1911 chambered in .45 ACP. In the early 1930s, Texas leatherworker and machinist Hyman Lebman converted 1911 pistols into compact automatic weapons. His design added a heavy muzzle brake, a Thompson-style fore-end, an extended magazine, and a vertical front grip, creating a compact automatic pistol often described as a miniature Thompson. The United States Army reportedly tested these pistols and achieved around 2,000 rounds before experiencing failures, notable performance for a high-rate-of-fire .45 ACP platform of that era. Two of the most infamous users were John Dillinger and Baby Face Nelson, who acquired Lebman pistols while posing as Texas oilmen and used them in bank robberies rather than self-defense. Lebman was later charged under the National Firearms Act and for involvement with organized crime. The host links these events to the origins of restrictive U.S. gun laws that still limit civilian access to such automatic pistols.
Attention then shifts to the Magpul FMG9, a folding 9mm concept gun first shown in a video from SHOT Show over a decade ago. The FMG9 resembled an awkward flashlight or compact briefcase when folded, with the outer shell appearing almost like a large battery pack. In a threatening situation, it could be unfolded into a functional firearm, revealing a compact 9mm platform concealed within the housing. The concept generated significant interest among enthusiasts, but after the initial demonstration, there was little public progress toward production. Years later, Magpul and Zev Technologies announced the FDP9, a development of the original folding gun idea that many viewers had been waiting for. However, after that announcement, information again became scarce, with no clear release timeline. The host expresses interest in the FDP9 and even suggests a potential giveaway package built around it if it ever becomes a commercially available reality.
The list then moves to the Hellriegel, widely recognized by many players from Battlefield 1, where it is portrayed as a highly effective weapon. In reality, the Hellriegel 1915 was an experimental, cumbersome early automatic firearm developed in the 1910s. It fired a 9x23mm cartridge, also referred to as 9mm Steyr, similar in concept to modern 9x19mm. The gun used a large drum magazine that was often mistaken for a belt-fed system because of the material strip visible on top, though it remained drum-fed rather than truly belt-fed. Some versions could also use a 20-round magazine. The Hellriegel was water-cooled, adding significant weight and bulk. It offered a high rate of fire but never progressed beyond experimental trials conducted around 1912 to 1915. While it stayed a prototype, it stands out as one of the earliest attempts at a high-volume, shoulder-fired automatic weapon, contrasting with later successful designs that refined the concept.
The number one pick is the Heckler & Koch G11, a radical bullpup rifle that nearly replaced the G3 as Germany’s standard service rifle before the G36 was ultimately chosen. The G11 fired caseless 4.73x33mm ammunition, eliminating traditional brass cases and allowing a compact, high-capacity magazine holding roughly 45 to 50 rounds. The small cartridge size made such capacity feasible without an oversized magazine, similar in concept to how the FN P90 carries 50 rounds of 5.7x28mm. HK’s interest in small-caliber, high-velocity designs is echoed later in the 4mm-class MP7 cartridge. Development of the G11 began in the late 1960s and continued for decades, including variants with an integrated optical sight and even a bayonet option. Despite its advanced technology and near-adoption, the program was canceled in favor of more conventional solutions. The video closes by noting how these experimental guns influenced later designs, intersected with changing firearms laws, and remain notable for their ambitious engineering even though most never saw widespread service.
Loading... 
