OK, geek alert. This is a seriously geeky post. If technical stuff makes your eyes roll up in your head read no further.

Let’s talk about the guns in the Dwarven Rifleman. These guns are big-bore spring-piston airguns because Battlemages in their world can detonate ‘blasting powder’ at a distance, so conventional firearms, while certainly within the technical prowess of the dwarves, are a Very Bad Idea.

In our world large-bore airguns have a distinguished history starting in the 16th Century. The first such airguns used a leaf-spring to compress a bellows in the butt-stock to fire a dart. These were used mainly for target practice, but there are some indications that they were used on small game as well.

Next to come along, both at about the same time, were guns that used a pressurized air tank and spring-piston guns. These types fired the same sort of lead balls that were used in muzzle-loading firearms and were comparable in power. Some were smooth-bores, some were rifles and there were even some large-bores that could be fitted with a smooth-bore sleeve to fire shot loads. Spring piston guns were relatively rare, however, because it was very difficult to make a spring of sufficient power and quality to last for very many shots.

At their apex around the turn of the 19th century powerful repeating airguns were in limited military service with the Austrians, the Japanese and a few other forward-looking nations. The Girandoni was the most famous of these. These were .49 caliber, 22-shot repeaters. The air tank served as the butt-stock and when exhausted could be unscrewed and replaced with a fully charged tank. These guns were lethally accurate at ranges up to 150 meters. In an age where the standard military arm was a muzzle-loading smooth-bore that fired about 3 shots per minute, with an effective range of fifty to sixty meters, they were practically a machine-gun. The problem is that they were relatively fragile, difficult to maintain in the field and very expensive to make. Modern large-bore airguns range from .357- .58 caliber and are quite capable of taking large game.

The airguns in the Rifleman’s Universe are of the spring-piston type. These are simple designs compared to the pressure-tank type guns, but require very sophisticated metallurgy and manufacturing. In these guns a trigger releases a piston, which is driven down a tube by a powerful coil spring. The air compressed by the piston fires the projectile. Modern guns of this type fire pellets of .177 to .25 caliber that weigh from 4.5- 31 grains. These guns are designed to optimize their performance with small, light projectiles and all calibers use the same power plant and same aperture size for the air to enter and propel the pellet. So while the .177 pellet leaves the bore at 1200 feet per second the .25 manages maybe 700 feet per second. While these are not toys and are quite dangerous, they are hardly suitable for offensive or defensive use against people.

Based on these modern guns many people scoff at the idea of large-bore spring piston guns. The spring would have to be so powerful that a person couldn’t cock it is the usual objection, but in a properly designed gun this isn’t true. Modern guns all use the same size hole for the air to enter the bore, and this is idealized for small-caliber pellets. But in the larger bores this slows down the flow of air behind the projectile and reduces the muzzle velocity. They don’t take advantage of the volumetric efficiency of the larger projectile diameter.

Let’s keep this simple- a 9x19mm handgun uses 25,000 psi to propel a 125 grain bullet at 1,100 feet per second. But a 11.25x 23mm (.45 ACP) cartridge uses only 13,000 psi to propel a 230 grain bullet at 850 fps. This same effect can be taken advantage of in an air rifle.

I did a lot of math on this, and I am not going into that here. You’re welcome. A typical modern air rifle that fires a .25 caliber/31 grain projectile will, if a .30 caliber barrel is mounted, fire a .30 caliber/61 grain bullet at about 400 fps. With no changes to the power plant (the spring-piston and compression tube.) This is actually getting into the genuinely dangerous-to-humans range. But if the power plant is modified to allow the air to enter the bore more quickly the gun will fire the same .30 caliber projectile at approximately 500 fps. Increase the diameter of the piston and the power of the spring and 1000 fps is easily attainable- without being un-managabley difficult to compress the spring. This would produce a weapon that was capable of bringing down man-sized game… or men.

The larger the bore the better it works. The math suggests that a .50 caliber air-rifle firing a heavy bullet at 800-1000 fps is doable and would not require excessive cocking effort. Thus the guns of the Dwarven Rifleman’s universe.

The Infantry Long Rifle used by the protagonist is described as a ’36-bore/325.’ This means that it is a nominal .50 calibre firing a slug 325% of the bore diameter, or an about 1-5/8 inches long and weighing about 800 grains, at a velocity between 800-1000 fps. With a good shot this would drop a Kodiak bear… or more to the point hammer through a goblin’s breastplate at 125 yards. These are the top-of-the-line guns in the story.

The Rangers and some skirmishers use a 36-bore (.50 Caliber) repeating carbine that fires a round ball and holds twenty shots. If I remember correctly the ball is about 173 grains and the muzzle velocity is around 1200 fps. The repeaters aren’t much faster to shoot than the breech-loading single shot ILR- but they are easier to cock and fire while mounted. These guns are rifled and have an effective range of about 150 yards.

Most soldiers are armed with ‘Slug Guns.’  The are 16-bore smooth-bore weapons, firing a one-ounce slug.  They are much shorter-ranged than the ILR and, like musketeers in our world, depend on volume-of-fire more than individual accuracy.  Of course in units of dwarves, where the average soldier has thirty years or more in service, individual accuracy can be better than you might think…

Various other guns are mentioned- one character has a 12-bore (.72 caliber) rifle, and while I don’t get into specifics this has to have some serious punch- and require a huge compression-chamber. It is, as the protagonist notes, “a lot of gun.” The protagonist’s father has a 14-bore (.69 caliber) smooth-bore that fires balls, shot or slugs. The smooth-bore makes it a relatively short-ranged weapon, but highly effective within that range.

Handguns are very rare but two handguns are mentioned- ‘the Hammer’ and one carried by the Prince. The Hammer is based on a scaled-down carbine action and fires the same balls, but at about 600 fps., making it about as powerful as a modern .38 Special 158grain target load. The Prince’s gun, while never really described (though it might be in following books,) is a very different proposition. It’s a single-shot breech loader representing the finest the dwarves can make. It fires the same 36-bore/325 slug as the ILR, but at about half the velocity. In modern terms this isn’t very powerful, but a one ounce, ½ inch diameter slug moving 550 fps will still seriously ruin your day. Because they need bulky compression chambers handguns are big- The Hammer is about twenty inches long and the Prince’s gun is similarly sized. They probably weigh in the neighborhood of four pounds.

So that’s pretty much as far as we can get into the guns without ‘spoiler’s.’ Except, of course, for the Tower Guns of Ironhame, but they are a story for another time.