Anyone working on a 3/4 to one inch version of the old gyrojet? That ought to be a big enough bore, but the recoil would be anemic.

tbob - The gyrojet was a idea who's time had not come. The projectile proved to be almost totally ineffective from the muzzle to 30 yards. The problem was energy was built over a long acceleration curve rather than a traditional bullet which leaves the muzzle at maximum energy. Another problem was accuracy. Since the bullet did not fully stabilize until it gain velocity, they tended to wander all over the place. The original design was not waterproof and the cost was considerably higher due to complex and exacting manufacturing.

James Bond would love one, however, just give me an AR-16 with grenade tube.

Somewhere in my brain I seem to recall that these were declared "destructive devices" and that open, public addess development is no longer being done.

I don't recall any RIFLE gyrojet firing devices. The original gyrojets were 13mm (ie: larger than .500 inch) so that when the one-half inch handgun limit was enacted, gyrojets were reduced in size to 12 mm. As implied (degradation due to moisture), gyrojets had very poor shelf-life.

the_captn

Talk to McUzi on www.full-auto.com He loves the gyro jet and he owned on for a while. I think he is working on building new ones. They are not destructive devices because the ATF has decided that they are curios and relics.

here is a rifle

I seemed to recall a recoiless 30-06 that released gasses to the rear by allowing the case to rupture in a controlled manner. It blew little discs out the right side of the chamber and allowed gasses to escape to the rear. I am unsure if this was one of the experimental weapons I saw in the military museums that I was fortunate enough to be allowed to see get private tours of or if it was a civilian rifle. I cannot imagine the extraction difficulties and other issues that must have followed a weapon of this desigh. it certainly would not have been practical for military use where there are usually people beside you.

As Zero Drift pointed out, with your gyrojet double rifle you'd still need a normal gun for short range protection. Perhaps a bayonet lug would fit the bill ala some English game keeper guns?

A few years back I read about a novel design for a low recoil 30mm aircraft cannon. When the shell was about 30% of the way down the barrel, the breech simple unhinged and let the propellent gas start to escape to the rear. This caused a low pressure wave, if you will, to progress up the barrel. It was timed such that it didn't quite catch the shell before it left the muzzle, and resulted in little velocity loss. Ideal gas law be damned, it still takes a finite amount of time to vent even when uncorked. I thought it an interesting idea that avoided the vastly increased propellant charges of other "recoiless" systems.