: What I am is a Sci-Fi geek and wannabe author. Last night I had an idea for
: a cool SF-type gun that instead of using different types of ammunition for
: different targets/effects, used powerful electromagnetic coils to shape a
: copper slug as it passed through the barrel, like your quarter shrinker. I
: imagine this dial-a-round system to be able to produce three shapes:
: Hollowpoint -- minimum penetration, but maximum tissue damage;
: Parabellum -- balance of penetration and damage; and
: Penetrator -- a long, thin, perhaps molten, round to punch through armor.
: My questions are:
: * Could such a system conceivably be built--I mean, would it violate any
: laws of physics?
You can deform and heat the slug - not a problem. However, forming it to the various shapes above "on the fly" does not look to be possible for a variety of physical and practical reasons.
Wouldn't it be easier to pre-select a projectile shape and then use a pulsed magnetic field to accelerate it to an ultra-high velocity? A rail gun can accelerate a projectile to a much higher velocity than can be attained through chemical explosives. Google "coil gun" or "rail gun".
: * Based on your description of the physics, I can see how a bullet could
: be squeezed longer and thinner, but could it be stretched out shorter but
: fatter, or squashed/stretched into a different shape, like from a
: parabellum into a hollowpoint?
I don't think so. If the bullet passes through the coil nose-first (the normal way), compression can only be in the radial direction inward (toward the central axis of the bullet). Forces pretty much balance only if you use an object that is radially symmetric versus the coil (such as a disk or cylinder-like shape). Trying to inject a bullet "sideways" (and then trying to modify
g the shape via a pulsed coil) disrupts the symmetry of the coil/bullet system, and the modified shape will no longer be "round".
: * Could such a coil be made to actually melt the copper slug? A hit from
: that could be devastating.
Given enough pulsed power delivered quickly enough you might be able to melt the slug as it passed through a coil. However, I would also think that a high-speed glob of molten copper would be adversely affected by aerodynamics before it could travel very far. Also, skin effect limits how much energy you can put into the bullet. If you try to inject energy too quickly, you vaporize the outer portion of the bullet, leaving a smaller but cool central portion. If you were able to create a supersonic jet of molten copper, it could be deadly to nearby armor just like current explosive-driven armor-penetrating devices.
: * Would passage through such an intense EM field affect the round's
: velocity? Accuracy?
Yes and Yes...
: I'd be thankful if you could help me.