|Bear Claw Left: A Square Solid Right: Photo Stuart Anderson Wheeler|
|Barnes Triple Shock X Bullet, monolithic gilding metal|
Some common sense comes into play here, you don't need a 500 grain monolithic solid to stop a charging Elk, nor would you use a 165gr expanding solid on Cape Buffalo. At least not if you had any sense of self preservation.
Take note of the driving bands on the A Square and X bullet. Traditional cup and core bullets do not need these as the lead core deforms easily, and the gilding metal jacket is thin enough that it deforms easily to take the shape of the rifling. Without those relief cuts or "driving bands" the bullet would cause a very unsafe spike in pressures and give extremely bad copper fouling in the bore.
Remember, penetration is more important than tissue disruption when it comes to lethality, so expansion becomes the least important feature when selecting a rifle bullet. However, if you are using a cartridge that is accurate, and fully capable of penetrating to the vitals, then choose an expanding bullet to maximize the lethality trio.
In the handgun world, monolithic solids have been labeled "cop killers." Back in the 60's three men Paul Kopsch (coroner), Daniel Turcos (police sergeant), and Donald Ward (special investigator) started experimenting with solid brass projectiles so that Police could shoot "barrier blind" ammunition (same problem the USMC and Army had with M855 and why the USMC adopted Mk318 SOST and the Army M855A1). They eventually settled on a solid brass bullet lubricated by polytetraflourinated ethylene (PTFE) or "Teflon." If someone tells me that KTW stands for "Kevlar Tipped Wadcutter" ever again I may suffer a stroke.
For some reason Hollywood took note of the teflon coating and decided that any bullet coated with teflon was an "armor piercing cop killer" to the point where a normal FMJ bullet sprayed with "teflon" pierces a vest in the movie "Ronin" and Mel Gibson can shoot 9mm bullets through the blade of a bulldozer in one of the "Lethal Weapon" fiascos. Teflon does very little for terminal ballistics, it does a lot to protect the bore of the pistol. Remember how lead was very maleable? Solid brass isn't. Normal cup and core bullets deform easily against the rifling of a steel barrel, solid brass not so much.
|KTW Bullets, truncated cone, PTFE coated brass|
Now, what is the future of monolithic bullets? I don't know, but the most interesting idea has come out of Italy. Compensated bullets.
With a "compensated barrel" a series of holes are drilled perpendicular to the bore which allows gas to escape sideways before the bullet exits the muzzle. This is to reduce muzzle flip and recoil. By drilling a hole in the base of the bullet and other holes perpendicular, the bullet acts as a compensator for a brief amount of time. That the bullets are solid brass instead of lead means they are lighter (less massive) and can therefore be driven at a higher velocities. Going back to our initial set of useful equations, E = .5MxVV or one half mass times velocity squared.
I can see the advantage of using this sort of bullet at relatively close range while retained velocity is high. More controllable rapid fire, and barrier piercing capabilities. I haven't had the chance to play with any of these, but I would like to.
The increase in velocity is key, reducing a 9mm mass from 125 grains to 100 grains will give you an increase in energy if you can add 40% to speed. And since the projectile is brass, it can hold together on impact even with the added force acting on it.
However, the reduced mass gives a reduction in momentum as velocity decreases, so don't expect compensated bullets to be miracles of ballistics.
I expect Hollywood to lead the charge in declaring these bullets (designed by a competitor for competitors) evil incarnate to make the importation even more illegal.
Other materials have been used for solids, such as Tungsten. Tungsten is a good choice because it is denser than brass (ironically it has the density of gold) and is quite hard. It makes such a good penetrator that several nations have stopped using Depleted Uranium (DU) fin stabilized discarding sabot rounds for the 120mm NATO standard main gun on tanks. Tungsten is damn expensive compared to brass though, and ironically the animals don't seem to get any deader for being shot with it.
In terms of defeating ballistic vests, you either need a bullet that will punch through, or enough energy that the bullet design doesn't matter at all. When gun banners talk about banning "armor piercing ammunition" they are really trying to ban all centerfire rifle ammunition, even in Grandpa's 30-30. You can look up the National Institute of Justice body armor standards, NIJ 0101.04 for yourself.