Concealed Carry & Home Defense

HOOBER: Explaining To Alec Baldwin How A Single Action Works

(Photo credit: Twitter/Screenshot/Public-User: ABC News)

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By Sam Hoober

Alec Baldwin almost certainly pulled the trigger, resulting in the gunshot that killed Halyna Hutchins. It’s true that fault in this case would appear to lie with multiple people; we can debate how much is his later.



He says that he didn’t. There is a narrow set of circumstances in which it’s plausible he didn’t, but it would be very rare indeed for it to be possible and that has to do with how a single-action pistol works.

It’s more likely that he doesn’t remember that he did, or doesn’t believe he did as a defense mechanism. Disagree all you want, but the stuff they cover in Pysch 101 tends to explain a heck of a lot of human behavior pretty well.

Single-action operating mechanisms for firearms are actually the most common, and don’t think for a minute that changing hammer-based mechanisms for striker-based mechanisms meant that single-action pistols were a thing of the past.

In fact, some of the most common striker-fired pistols are actually single-action; it’s just that most people hear or read “single-action” and think of a revolver or a Browning-designed pistol like a 1911 or a Hi Power.

Sidebar: if Remington were to create a DA revolver styled like the 1858/1875, I would make a very stupid financial decision because of it.

The defining characteristic of a single-action system is this:

The firing mechanism itself – be it the hammer or a striker/firing pin assembly – is placed under full spring tension and held in place by the sear. In order for the firing mechanism to be released and thereby discharge a cartridge, the sear has to be acted upon by the trigger. You pull the trigger, which pushes the sear out of the way and releases the hammer or firing pin/striker.

A pin strikes the primer, cartridge go boom, and the bullet goes down the barrel.

Exactly how that’s done depends on the gun.

Hammer-fired guns all work the same way; it’s just that the hammer is sometimes installed in a semi-auto rather than a revolver!

The hammer is linked to a strut, which depresses the hammer spring. The hammer itself has a couple of little hooks machined into it, which catch on the sear. Essentially, the way it works is the hammer rotates, and as it rotates to full-cock (when the hammer spring is totally depressed) then the hooks catch the sear and hold the hammer in place.

The difference, of course, between DA revolvers and DA/SA pistols and the single-action variants is that a DA system also adds a disconnector link to the hammer. The disconnect link is what the trigger pushes on to bring the hammer to full cock without doing so manually.

That’s how a Colt SAA works, and that’s also how a 1911, a Hi Power and indeed any hammer-fired pistol works in terms of the firing mechanism.

Striker-fired pistols with a true single-action mechanism are a bit different, but mostly the same; cycling the slide fully compresses the firing pin/striker spring and then the sear catches the firing pin assembly at full compression, holding it in place.

Single-action striker-fired pistols include Sig Sauer, Walther, Smith and Wesson, Heckler and Koch and other popular makes and models. Glock pistols, it must be mentioned, are effectively halfway between double- and single-action; the striker assembly is partially tensioned by cycling the slide.

Different ways of doing it, but it’s basically the same thing in the end.

Incidentally, semi-auto rifles and shotguns work the same way; hammer hooks catch on a sear hook, which holds the hammer in place until the trigger is pulled and the hammer is released.

So, how could it be possible for a single-action pistol of any kind to discharge without the trigger being physically pulled? Is it possible at all?

In theory and in fact, yes, but only up to a point.

Trigger jobs are a thing.

While the best practice is to install new parts that have had modifications done by the factory, some people will have a gunsmith modify the sear and/or hammer for a lighter or crisper trigger pull. Or worse, they’ll do it themselves.

If too much material is filed away from the sear or hammer, a consequence may be that the hammer is far more easily released from the sear hooks. If that happens, sufficient vibration can allow the hammer to fall such as in case of a dropped pistol or sufficient vibration caused in other circumstances.

The sear and/or hammer can also become worn with enough time and use, so the sear and hammer hooks don’t engage as positively as they should. This leads to the same scenario.

Whatever the case may be, if anything results in less positive engagement of the sear and hammer or striker/firing pin assembly, that creates the potential of a true accidental discharge.

It so happens that a common modification to single-action revolvers (especially for CAS/SASS competitors) is trigger tuning, and any gunsmithing is only as good as the person doing it. Whether the movie gun in question was modified is anyone’s guess, but the point here is that it’s very common for Colt SAA pistols and their clones to have an action job.

But in the case of an unmodified gun, unless the factory made a serious mistake that didn’t get caught by QC, the reality is that any single-action gun is not going to “go off” except for a drop-fire or if the trigger was errantly pulled. Given the short travel of single-action revolver triggers (even modern double-action guns have a short single-action pull) that would seem far more likely.

What do you think? Did he probably pull the trigger without thinking about it? Do you believe him? Do you have any single-action revolvers? Let us know in the comments!

Sam Hoober is a hunter and shooter based in the Inland Northwest.