Of Minnie-Balls and Dum Dums

Milestones in the development of small arms ammunition.

Firearms at the time of the American Civil War (we're talking long guns, not pistols here) came in two types. Smooth bore muskets and rifles. Rifles, as the name implies, had rifled barrels. Rifling a barrel means cutting a series of grooves into the interior of the barrel so that when the bullet is fired spin will be imparted to it. This spin gives the bullet gyroscopic stability and has the effect of making the bullet fly straighter.

The advantages of a rifle are clear. A smooth bore musket was accurate only out to about 50 feet. The bore of the musket was larger than the diameter of the musket ball so as to make loading easier and faster. This meant that the ball when fired would literally bounce around the inside of the barrel as it was fired. When exiting the barrel it would rarely be going in exactly the direction that the shooter was aiming.

This is why infantry battles were fought by massed ranks of soldiers standing shoulder to shoulder firing at each other from short range. To hope to hit anything you had to get close aim in the direction of the enemy and trust to luck that you would hit something. With a rifle, however you could accurately pick off enemy soldiers out to 250 yards.

So why didn't all the armies of the world switch to rifles? Because rifles were slow to load. In order to get the accuracy that rifles are capable of the bullet had to fit tightly into the barrel. This meant that it had to be forced down the barrel with a ramrod and this took time. A musket can be loaded and fired twice (or more if the soldiers are well trained) for every one time a rifle is fired.

This speed issue made the smoothbore musket queen of the battlefield until 1848 when a captain in the French Army named Claude E. Minie invented a new kind of projectile. The "minnie-ball" as it came to be called was actually shaped like a modern bullet.

The genius of the minnie-ball was its hollow base. As the rapidly expanding gasses generated by the explosion of the gunpowder filled the base of the bullet it would expand, like a balloon being inflated, and cause the grease filled bands to engage the rifling. Because the projectile was smaller than the bore of the rifle it could be loaded as quickly as a musket, but it had all the accuracy of the slow-loading rifles. It was literally the best of both worlds and it revolutionized warfare.

The next development in small arms ammunition was originally developed for the infantry rifle, but ended up being banned for military use by international agreement. Instead the Dum-dum bullet, or rather its modern descendant, has taken over the ammunition market for police and armed citizens.

With the invention of Cordite, a more efficient propellant than black powder, projectiles (bullets) could be driven at higher velocities with a better chance of hitting a target at a longer range. However this caused recoil to become an issue. Firearms designers had compensated for the low velocities which black powder propellant produces by using large diameter (caliber) projectiles.

Driving the large caliber bullets at the higher velocities make possible by Cordite gave them an unacceptable level of recoil (the "kick" one feels when firing a gun). Firearms designers responded to this by designing rifles which fired smaller caliber bullets. A smaller (therefore lighter) bullet driven to the same velocity produces less recoil.

However smaller bullets do less damage to the target than larger ones and therefore have less stopping power. In 1890 British engineers at the arsenal at Dum Dum, India (near Calcutta) developed a bullet that would deform upon impact with the target. They did this by removing the copper jacket from the tip of the bullet. The use of higher velocity bullets had led to bullets being clad in copper jackets in order to keep them from torn apart by the barrel's rifling during firing.

By leaving soft lead exposed at the tip of the bullet it was able to deform, or mushroom, upon impact. This deformation of the bullet causes more of the kinetic energy of the bullet to be transferred to the target causing increased destruction of tissue and bone. Also as the bullet mushrooms its diameter increases causing it to contact more tissue as it moves through the body. The area of tissue which is actually contacted by the bullet and is crushed or cut by it is a major factor in the effectiveness of the bullet.

British engineers later improved upon the design further by adding a hollow cavity at the tip of the bullet. This gave the British Army's smaller caliber infantry rifle the same stopping power as the old .45 caliber Martini-Henry, but with significantly improved range.

Now enter the diplomats. At The Hague Convention of 1899 German representatives presented evidence of the massive wounding caused by British designed hunting ammunition and asked that "explosive" (meaning expanding) bullets be outlawed under international law. The Germans neglected to mention that this would give the advantage (at least in their minds) to the newly developed German Spitzer bullet.

The Spitzer was a pointed projectile fired at supersonic velocity. Upon entering the body it would tumble, or rotate, 180 degrees. This rotation would dump energy into the target and create a larger wound channel like an expanding bullet would (at least in theory). The Spitzer bullet was sometimes called the "latent dum-dum". In practice the Spitzer proved a poor stopper. It was observed that men shot with the German 7mm Mauser would often be able to return to duty within week or less.

The United Kingdom did not agree with the German Empire about the issue of expanding bullets, but did not press the issue so they were banned. The United States never ratified the Hague Convention, but follows some of its provisions.

Although the hollow point bullet is not used for military applications they have come to be nearly universal for law enforcement agencies and armed civilians.

Next chapter:

From Super-Vels to Hydra-Shocks. Handgun ammunition comes of age.

Inspiration for this post provided by Shooting The Messenger