Automatic Pistol Actions

[giggitygiggity]

What is the difference between pistols that are Single Action (SA), Double Action (DA), Single Action/Double Action (SA/DA), and Double Action Only (DAO)? I easily get the terms confused. Which action yields the lightest trigger pull? Thanks.

 

[The Wiry Irishman]

Single Action: The only action the trigger performs is dropping the hammer. The hammer is cocked in some other way, via slide movement or your thumb.
[think 1911, Hi-Power]

Double Action: The trigger performs two actions, the first is cocking the hammer, the second is dropping it to fire the gun. All the force required to do this comes from the force you apply to the trigger.

SA/DA: Typically carried with the hammer down on a loaded chamber, SA/DA pistols have a double action first shot (the long heavy DA pull acts as another safety mechanism) and for subsequent shots the hammer is cocked via slide movement for single action trigger pulls.
[think Beretta 92, Sigs, etc]

DAO: Like the above, only the slide will not cock the hammer. Ever trigger pull will be performing the dual actions of cocking and firing the gun.
[Not many guns are designed with this action type in mind. (a THR member one described DAO pistols as "an affront to His Holiness John Moses Browning and his Prophet on Earth, Jeff Cooper") but are frequently offered as options on guns designed for other trigger actions, like the Beretta 92 G (i believe that's the right letter), Para LDA, Sig and HK have one as well]

 

[EOD Guy in VA]

There are a lot of superb DAO pistols on the market and they are excellent for personal defense since every pull of the trigger is exactly the same as if you were firing a revolver. They are very popular with Law Enforcement. Some examples come from the finest manufacturers in the business, such as:
HK P30 V2 LEM
SIG P229 or P239 with the DAK trigger
Beretta PX4 Storm Model D

 

[mljdeckard]

If DAO pistols are excellent for PD because their trigger pull is consistent, how are they better than pistols that are SA ONLY with a single kind of trigger pull?

You know who likes DAO pistols? ADMINISTRATORS of cops because they want to babysit their guys and don't trust them to carry a gun without redundant safety features.

 

[EOD Guy in VA]

mljdeckard... since your mind is already made up and you're not really interested in learning, there's no sense in explaining further. :banghead:
Somehow, I think when H&K, SIG Sauer, and Beretta all produce DAOs, it's probably a pretty sound trigger option.

 

[Snowdog]

Then there are those who like 'em all. I love my K9's butter-smooth DAO trigger. I love my 1911's crisp SA trigger. Personal Preference: One of the finer allowances freedom grants us.

 

[The Wiry Irishman]

Somehow, I think when H&K, SIG Sauer, and Beretta all produce DAOs, it's probably a pretty sound trigger option.

Most major service pistol manufacturers offering a DAO option doesn't mean they're good, it just means there's a market for them. mljdeckard was right on the money as to where that market comes from: LEO administration and their legal representation looking to reduce potential liability and accidental discharges under the mistaken assumption that a trigger mechanism can be a substitute for proper training. The only objective reason I could see someone who actually shoots selecting a DAO where another option is available on the same gun would be a life-long revolver shooter wishing to make the transition to semi-auto.

 

[9mmepiphany]

The only objective reason I could see someone who actually shoots selecting a DAO where another option is available on the same gun would be a life-long revolver shooter wishing to make the transition to semi-auto.

that would cover almost all of LEOs who were working in the 80's

while i don't agree with their labeling...all Glocks pistols in LE are defined as Double Action Only

 

[EOD Guy in VA]

I have fired just about every trigger action known to man from flintlocks through HK's LEM. They all have their pros and cons and I enjoy shooting them all depending on the situation. The situation I’m talking about here is personal defense. Of the 40 handguns I currently have, I have chosen the HK P30 V2 LEM DAO as my primary concealed carry pistol. All of my alterative carry pistols are striker-fired S&W M&Ps. I want a trigger that does the same thing every time I pull it. It aids in muscle memory, consistency, and accuracy… for me. And, yes, it is a bit safer… what’s wrong with being safer.
No “administrator” made this decision for me, and I rarely fire a revolver.

 

[oneounceload]

And then there is the odd ball - the squeeze-cocking H&K P7.....

 

[9mmepiphany]

then there is the odd ball - the squeeze-cocking H&K P7

...SAO, the trigger's only function is to release the hammer

a real odd pistol is the H&K P9S...it could be carried
Cond. 1 - cocked and locked
Cond. 2 - hammer down on chambered live round with DA first shot
Cond. 2.1 - hammer down on chambered round, safety engaged with DA first shot
Cond. 2.2 - hammer down on chamber round, cocking to SA first shot using the cocking/de-cocking lever

 

[mljdeckard]

Yes, I arrived at that conclusion after reading a gun magazine article. You would be baffled if I told you I actually SHOT many of them.

 

[gc70]

I want a trigger that does the same thing every time I pull it. It aids in muscle memory, consistency, and accuracy… for me.

Based on this statement, EOD Guy in VA could equally prefer either SA or DAO, or both. The statement says nothing about the differences in SA and DAO and the rationale for chosing between those types of actions.

SA designs can have the lightest trigger pulls because all the trigger does is release the sear. The downside to a very light trigger pull is that the trigger can easily be pulled by accident; thus, SA designs usually have manual safety devices to prevent accidental discharges. SA designs require extra training to properly and consistently use the manual safety devices.

DAO designs have heavier trigger pulls because they both cock (or partially cock) the action and release the sear. The heavier trigger pull helps avoid accidently pulling the trigger; thus, DAO designs typically have no user-actuated manual safety devices. DAO designs substitute heavier trigger pull for manual safety devices, eliminating some user training and intervention in the firing cycle.

My beef with DAO designs is the seemingly constant effort to make DAO triggers lighter. My favorite DA/SA pistol has a 10 lb. DA pull and a 4.5 lb. SA pull, while my favorite DAO pistol has a 6.5 lb. pull. When a DAO trigger gets too close to the same pull as a SA trigger, the DAO's design rationale goes away and you are left with essentially the same dangers as a SA design, but without the offset of manual safety devices.

As noted above, the H&K P7 presents a unique solution. The P7 has a SA trigger and an automatic safety device which has to be manually disengaged to fire the pistol. However, the safety is disengaged by squeezing the grip, which is a pretty automatic user action when firing a gun.

 

[EOD Guy in VA]

gc70 says, “Based on this statement, EOD Guy in VA could equally prefer either SA or DAO, or both. The statement says nothing about the differences in SA and DAO and the rationale for chosing between those types of actions.”
As I clearly stated, my preference is primarily DAO, secondarily striker-fired. But since you asked… for concealed carry SAO e.g. most 1911s, is not a wise choice, in my view because you must a) take the extra unnecessary step of cocking the hammer, or b) carry the pistol “cocked and locked”. I tried the latter only to have the safety moved to the off position several times when inward-forward pressure was applied to a holster resulting in “cocked and unlocked”. I don’t know about you, but I’m not a fan of that mode.

gc70 says, “SA designs usually have manual safety devices to prevent accidental discharges.” Educate me… when I’m holding a 1911, safety off, and finger on the trigger, what device prevents the trigger from being pulled?

gc70 says, “DAO designs have heavier trigger pulls because they both cock (or partially cock) the action and release the sear.” That’s not always true… HK’s variant 1 has a pull of 4.5 lbs. identical to your SA. Para Ordnance’s LDA is even lighter.

gc70 also implied that DAO trigger pull weight is their only characteristic. Once again, that’s not always true. DAO triggers often have a longer trigger travel distance. A good DAO, however, like the HK LEM still allows for rapid follow-up shots by having a trigger reset of only 0.28”

gc70 says, “DAO designs substitute heavier trigger pull for manual safety devices…” and, “DAO's design rationale goes away and you are left with essentially the same dangers as a SA design, but without the offset of manual safety devices.” Again, not always true. The Para Carry’s LDA has a manual safety. Even light trigger pull systems like those on S&W’s M&P semi-autos have optional manual safeties.

I’m not trying to convert anyone to any particular trigger mechanism. I’m merely stating my personal preference, and accurately describing some of the options… which is the nice part of forums like THR… we can learn from each other.

 

[9mmepiphany]

As noted above, the H&K P7 presents a unique solution. The P7 has a SA trigger and an automatic safety device which has to be manually disengaged to fire the pistol. However, the safety is disengaged by squeezing the grip, which is a pretty automatic user action when firing a gun.

you actually don't dis-engage an automatic safety when you squeeze the front strap...you're actually cocking the striker. that's why they call it a squeeze-cocker...it's also the slide release, as differentiated from the separate slide stop

releasing your grip completely uncocks the gun...without ever having unblocked the striker

you can also draw and point the gun without cocking the piece...it just takes a different manual of arms

 

[JTQ]

EOD Guy in VA says,

gc70 says, “SA designs usually have manual safety devices to prevent accidental discharges.” Educate me… when I’m holding a 1911, safety off, and finger on the trigger, what device prevents the trigger from being pulled?

I'm pretty sure gc70 was probably referring to the thumb safety that in your example you switched off. Of course the 1911 does still have a grip safety.

(First off, I know EOD Guy in VA is not making an argument about the Glock, but I'll use it as an example simply because they are so popular with today's handgun owners.)

gc70 says,

My beef with DAO designs is the seemingly constant effort to make DAO triggers lighter.

I do agree with this point. Technically a Glock is probably not a DAO pistol (I'll leave the technicalities to the engineers), but is does have the simplicity for the user just like a revolver, requiring that you only have to pull the trigger to get it to work. The difference is that the standard Glock trigger pull is around 5 lbs which is basically the same trigger weight as my Colt 1911. In addition, a common modification for Glock users is the 3.5 lb trigger that they can even install at home. Conversely, my S&W 686 and 4506 both have 10 lb + double action trigger pulls and you can visually see the hammer come back which could also be considered another "safety" device.

EOD Guy in VA also says (referring to a 1911) ,

b) carry the pistol “cocked and locked”. I tried the latter only to have the safety moved to the off position several times when inward-forward pressure was applied to a holster resulting in “cocked and unlocked”. I don’t know about you, but I’m not a fan of that mode.

I don't doubt that it happened to you. However, I believe that to be an extremely rare occurrence for the vast majority of 1911 owners. Even without the thumb safety engaged you still can't pull the trigger either accidentally or intentionally without disengaging the grip safety. While I agree, I wouldn't intentionally carry my 1911 in Condition 0 (loaded chamber, safety off), in that condition it is still no less safe than a Glock or S&W M&P (not safety equipped) and people carry those pistols every day and don't even think about it as a safety issue.

 

[gc70]

EOD Guy in VA,

Your preference stems from the two most valid reasons to favor DAO: the manual of arms for a SA is usually more complex than for a DAO and; the possibility that a manual safety on a SA will not function properly.

As you note, some DAO triggers (LEM and LDA) are actually lighter than SA triggers and have very short resets. If you feel uncomfortable carrying a cocked and unlocked 1911, how could you feel comfortable carrying a DAO with an even lighter trigger?

Educate me… when I’m holding a 1911, safety off, and finger on the trigger, what device prevents the trigger from being pulled?

The brain. Seriously, manual safeties are to prevent the trigger from being pulled unintentionally, and not necessarily by the trigger finger.

-----

9mmepiphany,

you actually don't dis-engage an automatic safety when you squeeze the front strap...you're actually cocking the striker. that's why they call it a squeeze-cocker...it's also the slide release, as differentiated from the separate slide stop

Absolutely correct, but I find it easier to explain in safety terms to those not familiar with the P7, otherwise I get the inevitable "do you have to squeeze the grip to cock it after every shot" questions.

 

[9mmepiphany]

I get the inevitable "do you have to squeeze the grip to cock it after every shot" questions.

good point...i've been using the P7 so long that i sometimes forget that there are folks who think it needs to be cocked each time or that it requires the same pressure to keep it cocked as to initially cock it

 

[EOD Guy in VA]

gc70 & JTQ... I mis-read the "manual safety" point... that'll teach me to post to a forum at 4AM :banghead: ... also partly because I never use manual safeties. They can fail, it reinforces my handling of handguns as if they are always loaded, and being able to draw-point-shoot with no intermediate steps. I completely agree, the best safety is the link between the trigger finger and the brain housing group.

My aversion to carrying 1911s cocked and locked is more rooted in my military background than the mechanics of the pistol itself. It just makes me uncomfortable. Not logical… just is. I know it’s not all that different from when I carry one of my M&Ps.

gc70…Regarding, “As you note, some DAO triggers (LEM and LDA) are actually lighter than SA triggers and have very short resets. If you feel uncomfortable carrying a cocked and unlocked 1911, how could you feel comfortable carrying a DAO with an even lighter trigger?” Answer: Because of the longer trigger travel with the first shot.

The seemingly never-ending variety of trigger mechanisms will always be a point of confusion and debate as long as there are handguns. On the other side of that same coin, there is a trigger system out there to fit almost every shooter if you look long and hard enough. I was not a fan of the DAO, or striker-fired system, for a long time. I grew up on the Army’s 1911A1, S&W Model 19 revolver, and the S&W Model 39 semi-auto pistol. It took a lot of time, and money, to settle on the DAO and Striker-Fired systems for personal defense… kinda like finding the right holster (please don’t start… )

 

[9mmepiphany]

kinda like finding the right holster (please don’t start… )

the long acknowledged measure of an experienced pistol carrier is the volume of his holster drawer(s)