OK. I've owned 2 Sig DAO guns, a 226 and a 228. Both were converted to DA/SA. But, I've never even fondled a DAK handgun.

Can someone please explain what a DAK is and how it works?

I know that DAK stands for Double Action Kellerman, and is Sig's current version of DAO but what makes it different, better, or worse?

Calling sigfreund!

Basically:

- DAK stands for Double Action Kellermann, after the designer.

- DAK has a lighter “full” trigger pull than DAO. It is typically around 6.5 lbs and most people who like DAK find it to be pretty smooth.

- DAK has an intermediate reset point which is about 8 lbs.

There is debate as to why the intermediate reset trigger is heavier than the full reset trigger. The purpose for the first reset seems to be in case of short-stroking, and the design of the hammer puts the trigger at the heavier (normal DAO) 8 to 8.5 lbs of force.

I can’t recall if the hammer is slightly pre-cocked at the full (long) reset, or if it’s just the geometry of the hammer and trigger mechanism working together to create the lighter pull.

Here is the Patent from 2004

Here is the U.S. version of the patent

IIRC,
The design was to have a lighter DA pull, the half step with the higher weight had something to do with it, but the DAK prescribed use is to go for the long pull every time.

quote:

Originally posted by GaryBF:
Calling sigfreund!

Indeed! I think he has a light that comes on in his kitchen when a DAK thread pops up.

He has the best handle on it from anyone here.

The old style DAO was a very simple design; the hammer is simply made without a single action cocking notch and therefore doesn’t stay cocked after the slide cycles.

The DAK system uses several redesigned parts, and puts the trigger bar in contact with the hammer at one of two points. When the trigger is allowed to move fully forward, as when it’s at its normal rest position, and then pulled, the trigger bar contacts a large hook that extends down from the bottom of the hammer. Because that contact point is farther from the central pivot point than in the old DAO system, the mechanical advantage is greater and therefore the trigger pull weight is less.

If the trigger is released forward to the intermediate reset point, the trigger bar contacts a small stud that extends out from the hammer that’s closer to the pivot than the large hook. If the trigger is pulled at that point, the pull weight is greater than with the full reset because the mechanical advantage isn’t as great. The short reset pull weight is still less than the DAO pull weight, though.

Pull weights in DAK pistols vary like those in all SIG pistols. The original spec for the long pull was 6.5 pounds, but that was with the original mainspring that was the same as used in DA/SA pistols. That spring sometimes led to light strike misfires, and not long after a heavier spring with red paint was introduced for DAK guns (except the P239). That increased the pull weight somewhat. Although it depended on the gun, some of mine exhibited long pull weights over 7 pounds, though many were in the 6.5 pound range.

The purpose of designing the DAK trigger with an intermediate, short reset point is debated. When I got my first DAK pistol, its reason was obvious to me: to reduce the length of the reset. One of the chronic complaints about the old DAO pistols was that the trigger had to move fully forward to reset. That never bothered me when my pistols had DAO triggers, but there was considerable whining about it among its few users. The DAK system addressed that perfectly: When firing a string of shots, let the trigger reset to the short point, pull again, and keep shooting. I and many other DAK users who’ve commented on the issue don’t notice the somewhat higher pull weight when using the short reset at speed.

Later, however, Herr Kellermann who designed the trigger supposedly said that the short reset point was added as a way of avoiding short-stoking problems. It is true that the DAK trigger can help with short-stroking, but otherwise the claim makes no sense. I read many complaints about the long trigger reset of the old DAO system, but never once that people were short-stroking their SIGs on a frequent basis. So why that complaint should have ever even been taken into consideration would have been a mystery—if I had ever believed it. The “short-stroking correction” claim actually struck me as a way for SIG to avoid mentioning complaints about the long reset of the original DAO trigger. Better to claim that an innovation was to help poor shooters than to fix an old design deficiency. And of course, the DAK system didn’t eliminate the long pull of the initial shot in a string, so someone may have thought it best to not mention the length of the long or short trigger pull at all:
“Nozink to zee here; move along!”

Short-stroking is in theory possible with any trigger unless the shooter must remove his hand completely, as with a bolt action rifle. Sometimes people short-stroke triggers in other guns, but virtually all of them learn how not to do that without a mechanical backup to the design to allow firing the gun even if the trigger isn’t released all the way. In fact, despite its short reset option, it’s possible to short-stroke the DAK trigger as well, and for the same reason: the trigger isn’t allowed to go forward far enough.

But regardless of what the original designer of the DAK trigger system was thinking when he added the short reset option to its operation, it’s also a fact that many DAK shooters, including me and many of my students, just naturally fell into the habit of using the short reset for rapid fire strings. I also usually use the short reset when shooting for maximum precision; the heavier pull weight helps me control the trigger better.

Added: The hammer photos might help too. L-R: Standard DA/SA, sport DA/SA, spurred DAO, bobbed DAO, DAK.

This message has been edited. Last edited by: sigfreund,

quote:

Originally posted by jljones:

quote:

Originally posted by GaryBF:
Calling sigfreund!

Indeed! I think he has a light that comes on in his kitchen when a DAK thread pops up.

He has the best handle on it from anyone here.

quote:

Originally posted by jljones:
I think he has a light that comes on in his kitchen when a DAK thread pops up.

Well ..., maybe a small one.

Sigfruend,

Thanks much for the clear answer to the OP's question - one I've wondered about myself.

Jerry

I had a P239 I had converted to DAK and also a Sig Pro I converted myself to DAO by changing out the FCU.

DAK is a much lighter DAO-feeling pull, it’s actually two pulls, the full and the half

DAO is long and heavy, just think of the first pull on any DA/SA

quote:

Originally posted by PASig:
… it’s actually two pulls ....

This is a statement I’ve read many times. It unfortunately causes much confusion because no one ever says that about a SIG or Walther or S&W or … traditional double action/single action pistol, and yet it’s just as applicable to those guns, if not more so.

To help ensure people who are not familiar with the DAK trigger understand, it’s accurate to say that there are two “types” of trigger operations with the DAK system, the one when the trigger starts fully forward, and the one when the trigger is allowed to move only to the short reset position and is then pulled back for the next shot. But when the trigger is pulled, it’s one or the other, not both.

Once the shooter has started pulling the trigger to the rear after letting the trigger reset fully or to the short point, the pull characteristics don’t change in mid stroke. Most DAK triggers are very smooth, and although the pull weight varies depending upon which reset point is used, the shooter experiences only a smooth unchanging stroke sensation until the hammer releases and fires the gun.

Many people like me who are familiar with both have compared the DAK trigger to a well-tuned S&W revolver’s. It’s long, it’s smooth, and it’s lighter than many other double action triggers such as the initial DA pull of a SIG Classic line DA/SA pistol. If someone can handle shooting the first, most critical shot with a SIG DA/SA gun, he can shoot a DAK pistol as well. That is also true of the countless shooters who mastered firing double action revolvers at speed back when they were the most common law enforcement and other self-defense weapons.

What shooters who are accustomed to the traditional DA/SA pistol don’t have to do, though, is switch between the long, heavy DA pull to a light, short single action trigger.

After reading sigfreund's ( and thank you again), excellent explanation of the DAK function, watch this video to see it in action


https://www.youtube.com/watch?v=f3vdegxLjG0

This article explains the DAK pretty well to me, including the "two pulls" that PASig is probably referring to. Video also included.

https://www.guns.com/news/2013...-a-sig-dak-read-this

quote:

My latest experience with the SIG Sauer P226 hasn’t gone so well. Why? I point my finger at the DAK trigger system. DAK stands for Double Action Kellerman. Kellerman is (rumored to be) the wealthy man who invented the double action only (DAO) trigger. Interestingly enough, the DAK trigger is roughly only a 6.5-pound trigger pull. Like a DAO, the shooter will get that 6.5-pound pull consistently by releasing the trigger all the way back out for a full trigger reset. But the DAK is unique in that the trigger system allows a double-strike capability. In other words, there are two trigger resets and releasing the trigger half way will allow the shooter to take another shot with… an 8-pound trigger pull?

quote:

But the DAK is unique in that the trigger system allows a double-strike capability. In other words, there are two trigger resets and releasing the trigger half way will allow the shooter to take another shot with… an 8-pound trigger pull?

The above is a typical misleading statement about the DAK trigger that in this case gives the impression that a “double strike” is possible only if the short reset is used. It is true that using the short reset permits pulling the trigger again (that’s usually what a “reset” does), but it’s also possible to pull the trigger and drop the hammer again if the trigger is allowed to go all the way forward to the full (long) reset point. To reiterate once more something I’ve said countless times in these discussions, the short trigger reset is an optional use feature. Don’t like it or the concept is too difficult to understand and use properly? Ignore it and don’t use it. It’s impossible to make it any more simple than that.

And, of course, the DAK system is hardly “unique” in permitting a double strike; any traditional DA/SA pistol, including the Classic line of SIGs, permits pulling the trigger and striking the primer with more firing pin hits as many times as the shooter has patience for.

^^^^^ I agree. I suppose he should have really said, "rapid double strike capability", to distinguish it from the typical DA/SA or the normal DAO.

DAK is a DAO trigger system in which the shooter can, after the first shot, select a longer, lighter trigger pull or a shorter, heavier trigger pull.

All true DAO triggers involve a trade off between the distance the trigger travels and the weight of the trigger pull. More leverage (trigger travel) requires less pull weight and vice versa. Most DAO triggers on semi-autos traditionally had fairly short travel and more substantial weight (i.e. 8 pounds or more). The DAK system added a longer, lighter trigger pull, which was more like a revolver, to the earlier DAO trigger. SIG later used the longer, lighter DAO trigger mechanics by themselves (not DAK) in the P250.

quote:

Originally posted by gc70:
Most DAO triggers on semi-autos traditionally had fairly short travel and more substantial weight (i.e. 8 pounds or more). The DAK system added a longer, lighter trigger pull, which was more like a revolver, to the earlier DAO trigger.

I am not sure I understand everything you’re saying, so a couple of my own comments.

The original double action only (DAO) trigger mechanism of guns like the P220 and P226 were identical to the double action pull of the DA/SA guns. The only change to the mechanism was elimination of the single action cocking notch on the hammer, and therefore the hammer does not stay cocked after a shot. Although I did not test a large number of guns, the double action pull weight of the ones I checked were mostly in the 10 to 11 pound range, but a few were between 9 and 10 pounds. As expected, changing from a DA/SA hammer to DAO had no appreciable effect on pull weights.

The reduction in trigger pull weight in the DAK mechanism is evidently accomplished mostly by moving the contact points between the trigger bar and hammer farther from the pivot point, thereby increasing the mechanical advantage of the system. The long reset point is farther from the pivot than the short reset point, and therefore the long reset pull weight is less.

The DAK system does not change the position of the trigger in the pistol nor the distance it moves when pulling it to fire the gun. Triggers for DAK and DA/SA (or DAO) guns are all the same, and therefore there can be no appreciable difference in the shooter’s finger position when shooting or how far the triggers move (rotate) before the gun fires.

What differs between the DAK and DA/SA mechanisms is the amount of mainspring compression before hammer letoff and discharge. There is also a difference in mainspring compression between the DAK long and short trigger reset strokes. As discussed above, the first DAK pistols used the same mainsprings as DA/SA models, and it was evidently found that because of the reduced spring compression, light strike misfires could occur with some ammunition. That led to the development of the “red paint” mainspring for use in DAK pistols. Because that spring is more powerful, its use resulted in a slight increase in the pull weight over using the DA/SA spring. (I increase the mainspring compression even more in my guns by adding a spacer in line with the spring.)

(As a technical tidbit, the NYPD contract overrun P226 I have was equipped with the same DAK mainspring even though the trigger was DAO, not DAK. Use of that mainspring in the contract gun was evidently due to that agency’s institutional belief that unintentional discharges are due to “light” trigger pulls; out of the box its pull weight was a horrendous 13 pounds, 1 ounce.)

One other difference between DAK and DA/SA pistols is the DAK mechanism uses a somewhat lighter sear spring. That, like compressing the mainspring less and moving the contact points between hammer and trigger bar, helps reduce the overall trigger pull weight.

This message has been edited. Last edited by: sigfreund,

quote:

Originally posted by sigfreund:

quote:

Originally posted by gc70:
Most DAO triggers on semi-autos traditionally had fairly short travel and more substantial weight (i.e. 8 pounds or more). The DAK system added a longer, lighter trigger pull, which was more like a revolver, to the earlier DAO trigger.

I am not sure I understand everything you’re saying, so a couple of my own comments.

We are saying the same thing in different ways.

quote:

Originally posted by sigfreund:
It’s long, it’s smooth, and it’s lighter than many other double action triggers such as the initial DA pull of a SIG Classic line DA/SA pistol.

From its full reset point, the DAK trigger (and the P250 trigger) has a long, light pull. From its short reset point, the DAK trigger is akin to the DA or DAO triggers more commonly encountered on other pistols.

Others have explained it well. I really like the DAK trigger, but it is an acquired taste.