A Slight Pressure on the Trigger

Not long ago, I ran across a news story about the U.S. Army's latest infantry weapon, the XM25, a "smart" grenade launcher using a laser rangefinder, onboard computers, and programmable ammunition to explode small grenades above an enemy hidden from sight. It's a case of exporting a difficult skill to a machine with an easy-to-use (dare I say point-and-shoot) interface. Armies around the world have a long history of this; you could reduce the entire history of firearms to this one theme without undue distortion.

This off-loading of skill has followed three arcs. The first made it easier to fire (or use) the gun. The second facilitated rapid fire. The third simplified hitting the target.

The first guns were awkward things fired by touching a coal or heated wire to the powder while holding the stock under one arm. Hitting anything at all was chancy. First the coal was replaced by a slow match, a smoldering, yard-long coil of treated cord that functioned much like a punk on the Fourth of July. So the soldier could keep his eye on the enemy when firing, a long, S-shaped, hinged rod (the serpentine) was introduced to mechanically lower the match into the power. As yet there were no triggers. The serpentine had to be balanced with the fingers of the right hand preventing premature firing, thus with the addition of levers and springs for control, the trigger was invented. A slight pressure on the trigger at the right moment fired the gun with minimal distraction. This was the first real user interface in firearms.

For over two hundred years this was the dominant system, but after 1650 was gradually replaced by the flintlock, wherein a piece of flint was driven against a piece of steel, sending a shower of sparks into the powder. It was easier and safer to use, as having a burning match around loose gunpowder was always an invitation to disaster. Flintlocks were also more reliable, misfiring half as often as matchlocks. After 1811, mercury fulminate, which explodes when struck sharply much like the cap in a cap gun, began to displace flints. Again, it was more reliable and easier to use. (With each change, the amount of effort in loading and firing the gun decreased.) By 1860, the modern methods of firing were in place.

The second arc was to make loading and firing faster. Each of the innovations just described made the process a little better, so that an experienced soldier in 1815 could fire six to ten times faster than one in 1500. So long as guns remained muzzle loading (loaded from the far end of the barrel), little more could be done. To make them faster (and easier) to load, they had to be loaded from the breach, leading to leakage of gas. Various things had been tried before 1800; however, the real breakthroughs came in the decades following the Napleonic Wars. Interchangeable parts and machine tools made all the difference. Guns were produced with finer tolerances between parts, which in turn meant less gas leakage. Then, with the introduction of fulminate primers, cartridges, which had previously been made of paper, began to incorporate metal. Originally just a metal disc to hold the primer was used,  later, cartridges became completely metallic. These expanded slightly when fired and making a tighter gas seal. Even better, since they were not crushable like paper, metallic cartridges could be fed from a magazine (either a box or tube with a spring at one end). By the 1860s a green horn armed with a magazine rifle holding seven or more shots, could fire faster than a drill sergeant armed with an older, muzzle-loading weapon. From that point on, repeating weapons have only become faster.

The third arc was accuracy. Initially, matchlocks and flintlocks improved this, as each required less attention than its predecessor, but the real star was rifling. It was expensive and took longer to load, so it was not popular before the second quarter of the nineteenth century, when the French found a way (the Minie ball) to create an acceptable rate of fire with muzzle-loading rifles using a conical bullet with an expanding base that created a gas-tight seal. This gave them and their British allies an advantage over the Russians in the Crimean War (1853-6), but it was the new breach-loading, repeating rifles that made the greatest difference. Firing and loading had been simplified to the point that a soldier could give most of his attention to hitting his target. For the first time, gun makers and ordnance boards began paying attention to sights. They worked out ways to make the sights simple and foolproof, so that less training would be needed to make a marksman. By the last decades of the nineteenth century, smokeless powder removed the last major obstacle to accuracy, eliminating the dense clouds of smoke created each time a gun was fired.

Over the last century-and-a-half, military rifles have continued to focus on creating weapons that are easy to use, fire rapidly, and are simple to aim. With the XM25, it appears we may have reached a new plateau, one where a computer does everything but select the target and make the decision to pull the trigger. It seems that everything else has been transferred to the gun. Will those functions also be externalized?