Jet bullets

I forgot to mention the bullet would be propelled to supersonic speed out the barrel by normal means and would already be going supersonic when the jet engine part is activated.
And yes it would be a ramjet or better yet a scram jet principle. At sea level the speed of sound is about 2,200 MPH or 3,300 FPS which is what a high powered 30-06 can achieve.

Now as far as fuel feed, a simple venturi effect might be enough to suck the fuel to the center of the bullet and feed the air flow right before a compression chamber of the scramjet. But if not I have an idea using an archimedes screw forced flow type of deal to counteract the centrifigual (centripetal?) force of the spinning bullet making the liquid want to stay along the outside walls of the tank.

With all this it would probably cost at least several hundred dollars a round to shoot.

During WWII, the Germans developed a ramjet artillery shell. It went nowhere.


However, we and other NATO countries use a rocket assisted projectile (RAP) round in 155 mm howitzers to extend range. They do lose some accuracy over conventional rounds if I remember correctly.

Movie VS Real life

They had them in movie "runaway" with Tom seleck

..

Same problem of decreasing weight over flight time as tracers, too.

I'm going to guess the reasons these haven't been developed are:

A) It'd cost about $100 per round.
B) It'd add another variable to the ballistics, making it harder to know where it's going.
C) Marginal gain in effectiveness over traditional slugs.

In short, the costs outweigh the potential benefits.

The advantage I see is a harder hitting bullet, not range. I’ve thought of such many years ago and thought I had a new idea, but then heard about the GyroJet.

Nothing new under the sun.

My idea was essentially a small rocket (GyroJet, again) with the exhaust directed at an angle to maintain spin. The bullet would take up almost all of the space of the case with an extremely powerful powder charge to expel it from the barrel at some high velocity, other wise it would drop considerably in the first few feet.

However, I didn’t see it as having a close-up use but, instead, be something to hit fast enough to spall the armor of a tank or bring down low flying aircraft—strictly a military round.

(sigh) Now back to getting that damn perpetual motion machine to working.

Now how about this idea for an application, an A10 Warthog sending a few thousand rounds of jet assisted 30 mm at an armored target. Might or might not be a thought and depending on the potential kinetic energy achieved might be a cost effective and enviromentally sound substitute for depleted Uranium. Or even better, what if depleted Uranium was usede as the fuel since depleted Uranium powder is so flammable in oxygen when heated.

Don't fix what ain't broken. The DU rounds used in the A10 work fine as is and I'm pretyy sure they are cheaper than your idea.