The Sig Sauer P229: Why the dual double action?

[Scruloose]

The CG has has started using the Sig P229 DAK .40, and as I’m going shoot it for the first time tomorrow, I got to get some hands on training and fam on one today. It appears to be a very good gun, but it has a curious double action feature that the Gunner’s Mates weren’t able to completely answer for me at the time.

Basically, this is a double action only weapon, with a trigger pull of about 6lbs. However, when the trigger is pulled, and the slide cycles, the trigger may be released half way out or all the way out for another pull. If you release the trigger half way, the next pull is about 8lbs. All the way out: about 6lbs.

So basically, after the first round is fired the shooter has the option of firing all rounds thereafter at either 6 or 8 pounds of pull, depending on how far you let out the trigger.

Can someone explain why this would be a feature on this gun?

Do other guns have this feature?

Thanks all.

[Cluricaun]

From what you describe, it sounds like this isn’t truly a “DAO” firearm, but a DA/DAO style, wherein the first shot, with the heavier trigger pull, is cocking the hammer back, while the next shots the hammer remains half-cocked unless the trigger is completely released and allowed to “decock” the firing mechanism.

[groman]

@Cluricaun

From what you describe, it sounds like this isn’t truly a “DAO” firearm, but a DA/DAO style, wherein the first shot, with the heavier trigger pull, is cocking the hammer back, while the next shots the hammer remains half-cocked unless the trigger is completely released and allowed to “decock” the firing mechanism.

The way I understand the OP, the trigger pull is actually harder when half-cocked, which is counterintuitive.

[Scruloose]

@groman

The way I understand the OP, the trigger pull is actually harder when half-cocked, which is counterintuitive.

That’s correct. The first trigger pull is actually lighter at 6 pounds. Then, every shot thereafter you can let out all the trigger for another 6lb pull, or let it half way out for a heavier pull.

Here’s a pic of one: Young Guns

If you’ll note the hammer, it is always in that position. There is no half cock feature, such as on the old Barretta M9.

[groman]

I don’t know that much about any particular gun, but from a pure physics standpoint, there is a mechanism in there that lets you accomplish the same work W (cocking and firing) by moving something two different distances. To dust off the old gem W = int( F * d ), if you reduce d you have to increas F to keep W constant.

So maybe the gun designer added another notch somewhere to let the gun cycle completely with half a trigger pull to allow for faster firing, as a side effect, the trigger pull became heavier.

[Padeye]

I have a feeling this isn’t an intentional feature but a consequence of how the trigger and firing pin lock are designed. Sig’s literature says it’s supposed to have a consistent trigger pull so you may be defeating that if you don’t let the trigger completely reset. I bet it’s something most shooters wouldn’t even notice unless they are used to a single action auto with a short trigger reset. I haven’t handled one of the DAK pistols and my Sig P245 has a standard DA/SA trigger and decocker.

[Cluricaun]

Hmmm…That makes absolutely no sense to me then…

I like it better when I can just make up answers.

[Scruloose]

@Padeye

I have a feeling this isn’t an intentional feature but a consequence of how the trigger and firing pin lock are designed.

It’s an intentional design, and I just found an article talking about this very subject:
http://www.shootingtimes.com/handgun_reviews/sig070606/index.html

The DAK Advantage
So what is this DAK thing? And why are people making such a big deal about it? In bare-bones description, the DAK mechanism provides a hammer-fired full-length double-action trigger pull, with complete repeat-strike capability, that is notably lighter than other full-length DAO pull mechanisms.
-snip-
After initial firing, the shooter can control the trigger reset either to an intermediate point with a shorter pull distance and two-pound heavier weight (the trigger bar intersects the hammer arm closer to the pivot point) or fully reset to the original longer and lighter weight position.

The article goes on to explain the hows and whys of this system, but I’m still not sure I fully grasp the why part. Perhaps I need to read it again and sleep on it. I’m a little brain-fried right now.

Anyway, shooting it today was a real treat despite the weather. I didn’t think I’d adjust too well without having the single action mode, but the light trigger pull provided for some very smooth shooting. I didn’t even bother firing it from the “intermediate” position.

[Padeye]

The article gives the mechanical reason the trigger behaves that way but I was able to find nothing that hinted at why it was designed that way. If I had to guess I would say it was so it would discourage a shooter from not doing a full reset but that and $4 gets you a cup of coffee these days. We just need to find who has the right answer. At any rate it’s nice to know you guys are getting quality arms.