
Sometimes, good ideas never get past the drawing board, like the RAH-66 Comanche. Sometimes, good ideas aren’t good ideas at all, like the F-35.
However, unlike the F-35, these project prototypes for military rifles failed to be adopted by the services they were hoping to win favor from. Still, you can run across these weapons from time to time- be it in video games, movies, civilian variants or serving with foreign armies.
Pancor Jackhammer
Designed as a solution to manually-loaded and lengthy shotguns, the Jackhammer passed all the trials the military set forth for it. Unfortunately, by the time the military got around to considering procuring it, the parent company had run out of funds from waiting for the military’s decision. Today, only one of the three prototypes is still in existence.
Despite this, the Jackhammer is featured in many, many films and video games- while it didn’t find use in our armories, it found its way into our imaginations.
H&K XM8
The golden child of the Ghost Recon series, the XM8 was a rifle that had a lot of promise during a series of trials originally part of the Objective Individual Combat Weapon program (OICW)- fancy military lingo for “expensive tests we do every few years only to decide to keep the M4”.
The XM8 was unable to meet the US Army’s requirements for weight and modularity, despite being a magical gun from outer space. Still, it found a home in limited numbers with the Malaysian equivalent of Navy SEALs, who totally see a lot of action with their H&K arsenal.
Colt ACR
If You had a GI Joe action figure in the early 90’s, odds are you probably had a toy replica of this rifle.
Considered high-tech for it’s time, the Colt ACR fired a cartridge that contained two bullets in one casing, allowing one round to land at point of aim with the other falling slightly below that to compensate for range.
Still, the rifle by itself was fairly remarkable at being unremarkable. Ultimately, it was scrapped in favor of keeping the M16.
H&K G11
Firing caseless ammunition and looking like a rifle mated with a boombox, the G11 is the most futuristic rifle ever made short of a railgun.
Requiring no brass casings, the ammunition was essentially wrapped in its own propellant. After initial small problems with ammo cooking off were fixed, the G11 was deemed a technical success.
Unfortunately, it was a political failure. Changing times and the reunification of Germany ended up killing the G11 in exchange for the famous G36.
Colt 703
The suggested solution to the jamming issues faced by early M16s in Vietnam, the 703 utilized internal designs similar to the AK-47 series of rifles. Unfortunately, when it was discovered that bad ammunition was the cause of most M16 malfunctions, it just made more sense to replace the ammo.
H&K XM29 OICW
Dang, H&K, you sure do make a lot of rejects.
Quite possibly the ugliest rifle ever made, the XM29 was part of the OICW project that involved mating a good rifle with a good airburst-capable grenade launcher. The equivalent of a grenade launcher mounted to a rifle mounted to an 80’s video camera, the ol’ 29 dwarfed anybody holding it.
While the program was scrapped for a myriad of reasons, it wasn’t a total waste- the XM25 Punisher grenade launcher was developed from the program and recently saw limited combat use in Afghanistan.
Bushmaster M17S

Okay, we take it back. This is an ugly rifle.
Developed to compete for the favor of the Australian Armed Forces, the M17S was originally owned by an Australian firm who sold it to Bushmaster after the Aussie Army decided to take the Steyr AUG instead.
During the dark ages of the 1990s assault weapons ban, the hideous M17S was the only American-made bullpup rifle to be offered commercially- and the only one not banned by name.
Now considered a relic by bullpup technology standards, versions of it made by another manufacturer can still be purchased today.
H&K CAWS
We began with a shotgun, so we will end with one.
Designed again by H&K, the CAWS was actually a pretty cool shotgun, taking the bullpup route for a 12 gauge lead sprayer.
Unfortunately for H&K, the US Military decided they didn’t want it. Even more unfortunate was the fact that H&K decided not to sell it to the civilian populace, where it likely would have been a commercial success.
Interestingly enough, these weapons are all featured in various video games, movies or animations- showing that sometimes form is more important than function… or government contracts.