A nice video describing the Gyrojet pistol. For those who somehow don’t know, the Gyrojet was a neat idea that just didn’t work out: a rocket pistol. The pistols (and associated carbine) were lightweight structures since they were not subjected to the usual stresses associated with firearms… rather than one high pressure explosion, the Gyrojet rounds were propelled by an internal rocket motor that burned for 0.1 seconds or so. While that was great for the firearm, it sucked for the bullet itself: muzzle velocity for the pistol version was about ten feet per second. Over the next fifty or so feet the projectile continued to accelerate to something like 1200 feet per second, creating a nicely lethal round. But the initial slow velocity meant that wind would easily blow the thing around… accuracy was a bit of a joke.
I’ve often wondered about modernizing the Gyrojet. Apart from the lame fixed internal magazine the firearm itself is fine, but the projectiles could do with an update. A two-stage motor would seem the way to go… a very fast burning first stage so that the muzzle velocity is stepped up to something meaningful, several hundred feet per second. Additional ballistics work to assure something resembling accuracy. Advanced versions with laser seekers and thrust vectoring.
Even the best modern Gyrojet will almost certainly be an inferior weapon compared to a proper automatic. But it’d make a dandy weapon for the Space Marines… the minimal recoil and low system mass would be useful for guys in space suits. Plus, it’d just be durned cool. And let’s face it, that’s reason enough.