#101

Revolvers are sometimes revered as being really simple self-defense tools compared to semi-automatic pistols, although, if you’ve ever seen the inside of one, you’d quickly notice that the operation is far from simple. I’ve enjoyed all sorts of wheelguns for decades now, but I was usually overwhelmed by trying to learn all of the internal components that make revolvers tick. Othais at the C&Rsenal YouTube channel has come to rescue me and those that have felt that same desire to know more, yet didn’t have a good 101 source, namely, Revolver 101, to lay it down in simple terms. Othais was generous in giving TFB permission to embed the video and to use some screenshots from it for TFB’s Wheelgun Wednesday.

In the first article discussing the mechanisms by which a firearm locks its breech, we mentioned briefly two quantities that are important for small arms design: Pressure, and bolt thrust. The latter we’ll discuss in a later installment, but today we’ll discuss pressure, and why it is important for both the downrange performance of a bullet, and the design of a firearm’s mechanism.

Previously in our introductory series on ballistics, we’ve discussed the concept of caliber, as well as ballistic coefficient and its close relative form factor. Today, we’re going to look at the concept of rifling, and how it relates to bullet stability.

Previously in TFB’s series on weapon operating mechanisms, we examined both the closed-bolt blowback system and the open-bolt API blowback system, two very close relatives that share a common feature: Closure of the breech through the inertia of the breechblock mass alone. What this means for small arms designers is that they must engineer a system where the breechblock is large enough to have sufficient mass, while having enough room to reciprocate the distance necessary for reliable ejection and feeding. In a standard submachine gun design using the API blowback system, for example, the breechblock is configured behind the breech end of the barrel, so that it can reciprocate. This is an easy design to engineer, and can be made simply and easily.

Previously on Operating Systems 101, we discussed the straight blowback method of firearms operation; today we’ll be talking about its close cousin, API blowback. “API” stands for advance primer ignition, which refers to the chief way that the mechanism differs from its pure cousin. We’ll get to that in a bit, but first we need to discuss the concepts of open bolt and closed bolt operation.

It’s no good to discuss how firearms work without also giving the context surrounding the firearms themselves. With that said, let’s talk about the AR-15, its copycats, competitors, and relatives. Together these rifles share space under the loose umbrella of black rifles, a term which references the use of lighter and more durable black polymer gunstocks in place of traditional wood, something that became common from the 1960s onward in military firearms design. Today the term simply means any modern military rifle, or any rifle patterned after a modern military rifle, the two most common of these by far being the AR-15 and AK types. For the purposes of this article, we’ll focus on the AR-15, but much of what we’ll talk about will be applicable to any black rifle.

Two basic mechanisms dominate the field of handguns today: The aforementioned straight blowback system, and short-recoil operation. The latter of two is a mechanism as clever as it is old; the first short-recoil weapons date back to the latter half of the 19th Century!