Why Glocks are NOT Double Action

	NRA Pistol Instruction Offered by Keith Manne NRA Certified Pistol Instructor

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Why Glocks are NOT Double Action

The problem:
Glock claims their guns are "Double Action Only". They are in fact striker-fire, SINGLE action, no matter what Glock and the box says. This misunderstanding has annoying operational implications, and possibly dangerous defensive implications.

Some Definitions:
Single Action: Pulling the trigger does ONE thing : if the hammer has been cocked, it will release the hammer. Trigger pull is light, short, and consistant between first and subsequent shots. Example: Star Firestar Plus.

Double Action: Pulling the trigger does TWO things : it will first cock the hammer if it hasn't been cocked, and then it will release the hammer. DA Trigger pull is longer and heavier than SA, but the user can cock the hammer first if they want to fire in "Single Action Mode." If the gun is semi-automatic, the first shot is DA, subsequent shots are SA due to the slide cocking the hammer for you, resulting in differing trigger feel as described above. Example : Beretta 8045, Hoekler and Koch USP series, etc.

Double Action ONLY: Any DA gun which does not allow pre-cocking the hammer because the hammer won't stay cocked, and is often bobbed or hidden. No decock is ever needed, and trigger pull is consistent between first and subsequent shots. Example: AMT Backup

Striker Fire: Rather than a hammer, an internal striker is cocked and released to fire. The striker is cocked by the first motion of the slide, and there is no way to decock other than squeezing the trigger.

So why aren't Glocks DA as claimed?

Any "true" double action gun will cock the hammer by squeezing the trigger, which means you don't HAVE to cock the hammer manually before the first shot as with a single action. In contrast, a Single Action gun you have to cock the hammer before you squeeze the trigger.

Glock claims to be "double action only" because :

1) You can't cock the hammer from a "hammer spur" externally, normally a sign that the gun is DAO.
2) In normal practice, pulling the trigger makes it go off, suggesting (falsely) that the trigger is cocking the hammer like a DA.
3) Trigger pull feels consistant between shots, suggesting DAO.

All three are wrong because :

1) Glock can be (and is) cocked externally for the first shot, but its done by the slide motion involved with loading the first round into the chamber rather than an overt hammer. This is true of any other semi-auto gun -- unless it really IS a DAO gun, any semi-auto can be cocked by racking the slide if you wanted).

2) The gun IS in fact cocked for the first shot before the trigger is pulled, and stays that way once cocked until fired, just like any other SINGLE ACTION. The second shot is cocked by the first, etc.

3) Just as with any other NON-DAO semi-auto, Glock counts on the process of chambering a round to cock the gun for you between shots. Since you always fire in single action mode, the trigger always feels the same.

Therefore, in practice, when you pull the trigger and it goes off, Glock wants you to think it's a DA, and not a SA which in fact is rarely loaded and still not cocked. If you were wondering why there isn't a decock lever on Glocks even though it's a wildly popular safety feature on any other good gun, it's because if you COULD decock the gun without it going off, you'd find that your gun is as good as a large paperweight at that point. You could simply bump the slide to recock the gun, but since Glock insisted it was DA, you won't know or think to do this. The bad news is, there IS a way the gun can get into that state, and it will most likely get there at the worst time possible.

How can I prove my Glock is Single Action?

There are a lot of Glock afficianodos who will SWEAR that their Glock is DA, until I have them dry fire twice in a row to similate a misfire. Remember what I said the definition of a DA gun is? DA cocks the hammer for you from the trigger, and will do so every time.

That's all interesting, but why is unexpectedly being SA dangerous?

People often buy DA for it's "panic mode" firing -- in a panic, you don't have to remember to cock it first as with a SA, just squeeze harder the first shot. I said before that Glock's claim to be DAO has gotten people killed. The case in which the gun is decocked unexpectedly is if you get a "misfire" due to a desensitized primer (one which takes more hits or a harder hit to go off). With a DA(O), you can squeeze the trigger again and get a quick second stroke. With a Glock, you only get one hit, because until you move the slide, the gun stays decocked.

Think I'm splitting hairs? If you KNOW how a Glock works, you know to bump the slide backward a little to re-cock it instead of staring at your traitorous gun dumbfounded at a critical time. In Personal Defense, I'd probably tell you to rack the slide fully and get a new round as soon as the one failed to go off, making the above point semi-moot, but then again, maybe it isn't:

I've encountered a LOT of desensitized primers. The most common reason is that cleaning solvent (eg. Hoppes #9) makes primers unreliable. You ask : Why would you clean your gun, reload it, and then fail to shoot it long enough for the primers to get funky? You SHOULD clean your gun before putting it away, and you SHOULD load your gun before you actually need it for defensive usage. Therefore, defensive usage is the most common time to discover this type of ammo failure. The primers aren't usually totally dead, but they often take a second hit before going off just fine if you stored them long in the gun. In an emergency, you aren't going to be looking to save the cost of that stubborn ammo, but you will be trying to save your life, and be too panicked to think clearly enough to tap the slide. It will be instinctive to pull the trigger a second or ninth time before it even registers that the gun didn't go off on the first try. You can marvel at the hard primer later, provided you didn't pull the trigger once with a click and 8 times with silence. That's why a gun advertised as DA should BE a DA gun, and should STAY a DA gun.

So what do I do now that I own a Glock?
With a Glock (or my own Steyrs), I would practice "dead round" drills until you are nauseous. Get comfortable with handling a dead round at the beginning/middle of a magazine. I recommend mixing snap caps in with your live ammo when you target shoot so as to surprise you when they occur (this helps with overcoming a flinch as much as handling malfunctions). As I said before, because loading the gun cocks the hammer, you shouldn't NEED to cock the hammer very often, but you might practice (with snap caps) finding how far the slide needs to be moved in order to re-cock the hammer (it actually isn't that much).