DA/SA or LEM/DAO, which is better for preventing NDs?

[BehindBlueI's]

Specifically in the context of holstering/unholstering, I doubt you'll see much (if any) difference. Unless you are holstering suuuuper gently enough to detect a snagged trigger, a 6lb s a 9 lb trigger isn't going to matter. No amount of travel is going to matter. Those are concerns for other scenarios, not necessarily holstering.

Something with a hammer/gadget is going to provide tactile feedback and the ability to stop the firing mechanism from moving before you complete the holstering...hopefully. A thumb safety (which I'm not a fan of) will allow for something to press the trigger without resulting in the gun firing as long as you remember to use it.

So, while I'm sure we could have a 38 page discussion on this particular angel dancing on this particular pinhead, the TDA/DAO/stiker/SAO seems like the wrong aspect to focus on in the narrow confines of the question. More broadly, there's a very lengthy thread on the differences in actual use, admin handling, etc already.

[Sensei]

I thought the FBI or sumbody did a study and determined that trigger travel, not trigger weight was more instrumental in reducing NDs, which is why LEM and DAK exist?

https://pistol-forum.com/showthread....-of-pull/page5

[YVK]

There’s a good argument that not needing to de-cock with a DAO/LEM provides less margin for error compared to TDA.

I agree.


In addition, irrespective of LEM vs DA/SA, gun ergos make a difference. To me not all DA/SA are made equal. I distaste DA/SA guns with beavertails for carry because beavertails often prevent effective thumb trapping of hammer. So you don't get a feedback if the hammer has been lowered in the first place, and whether there is an obstruction during holstering.

[jlw]

DA/SA will be marginally safer than the LEM. A 10lb DA trigger weight is significantly more difficult to pull than a 6lb LEM trigger if we are talking about objects entering the trigger guard during reholstering. The DA/SA has a more distinct hammer than the LEM if you are relying on hammer movement to let you know that something is amiss.

This presumes that NDs will only happen on the DA trigger pull. I know of numerous NDs that took place on SA via either the shooter keeping their finger on the trigger after they had fired or due to forgetting to de-cock.

[JonInWA]

JLW above hit it on the head-in my opinion, DA/SA IF DECOCKED generally will require more poundage to pull the trigger, so presumptively it'll give you a bit more of a margin for safety, whereas LEM provides both a hammer and a longer triggerpull, but a significantly lighter triggerpull weight (usually similar to the pull weight of a single-action or a striker-fired action).

But the DA/SA margin significantly resides in that the gun is decocked and placed in the DA mode before re-holstering (or otherwise further manipulating when the need for the SA mode has gone and the prudent thing is to decock into the DA mode).

If you're placing a digit on the hammer to restrain movement when re-holstering, I'd say either action is then equally safe/rendered more discharge-proof.

Arguably the key thing is operator headspace and timing; if you're not prudent in all actions with a firearm, something will probably inevitably come back to bite you, irrespective of the gun's action per se.

Best, Jon

[GardoneVT]

I know the best safety is the one between my ears, but we all make mistakes. Is a DA/SA less prone to NDs when holstering/unholstering, or is a DAO trigger like HK's LEM a safer? Why? Would appreciate everyone's feedback. Thank you!

Wish there was a direct answer . Unfortunately the data available only reinforces the obvious; you cannot fix a software deficiency with a hardware solution, regardless of the hardware in question.

I’m thinking of a German government study on their national police and NDs which, broadly speaking, concluded some officers under stress instinctively trigger checked their weapons.

[David S.]

There are smarter thoughts and maybe even studies that can demonstrate one is better than the other.

I know we're all about picking nits around here, but I suspect both are within the margin of error for its ability to help you prevent ND's. I'd say, decide between the two systems based on other factors.

[That Guy]

Are there any DA/SA guns with a concealed hammer that one couldn't put their thumb on?

Walther P99 is a striker fired TDA pistol. So not exactly what you asked, but similar. (You can place your thumb on the cocking indicator hole, but the end of the striker pokes out of it only at the very end of travel. I find it isn't terribly useful from the preventing ND while reholstering perspective. You're more likely to feel resistance during reholstering, rather than feel the cocking indicator right before the gun discharges but not feel the resistance from something in the holster pushing on the trigger. I do of course still place my thumb on the back of the slide when holstering a P99, but mostly for other reasons (verify the gun is decocked, prevent slide from moving out of battery, commonality of technique).)

[M2CattleCo]

I say LEM because the trigger pull is always long.

I don't think DA/SA protects the user from himself at all. The opposite actually. It adds controls and manipulations and complicates procedures.

I don't think DA/SA is bad choice at all for dedicated users, but they are absolutely NOT something that will protect you from a bone-headed moment.

[farscott]

If I understood the studies properly, increasing trigger travel distance decreases ND occurrences. Part of this is that the reflexive closure from being startled is much stronger than even the worst DA trigger. Part of it is shooters sometimes expect the DA press only to find the hammer is cocked. Part of it is that increased trigger travel distance allows for time to recognize the trigger press needs to stop. As such, LEM is better than DA/SA for NDs as every trigger press is long. That does not mean that NDs with LEM are impossible. LEM provides more margin, not infinite margin.

There is, for me, an additional benefit to LEM. Because every trigger pull is the same, holstering does not require decocking the gun like a DA/SA gun does. One less control and one less thing to do. Proper training and practice can make running the decocker second nature, but LEM eliminates the step from needing to be learned and done. LEM, of course, demands more practice and attention to that long trigger press to shoot accurately and quickly. For me, the safety benefit of LEM outweighs the difficulty of shooting LEM well.

Really there is no right answer. As a regular person, in the event I am forced to fire a shot in self defense, I want that shot to be deliberate and not accidental. I also recognize that I will likely be a bit shook after such an event. After the one encounter where I thought I was going to have to shoot, the adrenaline dump gave me a really bad case of the shakes. I shook so bad I set the gun down and sat down next to it. Not needing to decock or safety the gun was a nice plus.