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Is the p320 a true double action only where the trigger is the only thing that cocks the striker?
 

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No, the P250 is a true DAO.

The P320's striker is very substantially pre-tensioned (95%, 98%, 99%, or more?) by the slide cycling. The trigger only cams the striker back marginally to overcome positive sear engagement.
 

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There is a long thread regarding the P320 over on pistolforum in which a very experienced staff member states that the P320 striker is, in fact, fully tensioned by the slide cycle despite what has been stated by SIG. Apparently, he checked into this to determine the feasibility of fitting a device akin to the Glock "Gadget", which is considerably easier to do in a SFA pistol in which the trigger completes tensioning of the striker. I do not claim to know one way or the other.

Personally, I think classifying SFA pistols as SAO or DAO is rather misleading. The Walther P99 might be an exception, but I have never shot any striker-fired pistol where the trigger pull length and weight remotely resembled the trigger action of a double action only pistol, a DAO revolver, or the double action first trigger pull of an uncocked traditional double action pistol.
 

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Personally, I think classifying SFA pistols as SAO or DAO is rather misleading. The Walther P99 might be an exception, but I have never shot any striker-fired pistol where the trigger pull length and weight remotely resembled the trigger action of a double action only pistol, a DAO revolver, or the double action first trigger pull of an uncocked traditional double action pistol.
The Walther P99 is definitely a different kind of striker-fired pistol. The P99AS has a DA/SA trigger, with a long 9-lb. DA pull (with restrike capability) and a short 4.5-lb. SA pull, and a decocker to top it off. Walther formerly made a P99DAO that only had the long 9-lb. trigger mode, as well as a P99QA that used a partially-tensioned striker and a trigger pull of intermediate length and weight.

I would agree that classifying pistols only on the basis of whether pulling the trigger adds some unspecified amount of energy to the firing mechanism (striker or hammer) is misleading.

Manufacturers have a huge incentive to classify guns in a way that maximizes their saleability. If I remember correctly, one of Glock's first major US contracts was to the Miami PD, which had a DAO requirement because the Chief thought a long, heavy trigger pull was safer. The troops in Miami wanted a shorter, lighter trigger pull that would be easier to use. Glock was able to bridge the gap and got the contract. The FBI's current RFP for a 10,000-unit, $80 million handgun contract calls for "cocking by trigger pull" so manufacturers will use every possible arcane, technical definition to qualify their guns.
 

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I agree with planc in that it seems a bit misleading--a better option is just to leave the 320 in the Striker Fired category and not try and classify the 320 or any other SF pistol as DA or SA.
 

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I haven't played with the sig yet other than dry firing a local shop. I just ordered a .45 cary from the same lgs lgs. I do however own several M&P's and a gen4 Glock 17.

The M&P sear/striker engagement is totally unlike a glock. The pivoting action of the sear does not appear to do anything other than fall away from the striker much like most othwr hammer fired weapons. This in my opinion makes the M&P a single action, striker fired pistol. S&W seems to think of raising the striker block as the fist stage of the double-action pull.

On the Glock the sear is part of the trigger bar. When pulling the trigger the preloaded striker is moved rearward by the sear/trigger bar until the interaction with the trigger bar and connector cause the striker to fire. Decidedly double-action.

This is just my observation and I am totally open to correction.
 

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The problem I have with using (or arguing over) DAO and SAO labels for striker-fired guns is that they are practically never indicative of something that is observable, meaningful, and useful to a user.

Pick up a Ruger GP100 and a Ruger Blackhawk and pull the triggers. The Blackhawk trigger will do nothing if the hammer is not manually cocked - SAO! The GP100 trigger will cock and release the hammer - at least DAO! Manually cock the GP100 hammer and pull the trigger to release the hammer - DA/SA! You discover the proper label for the trigger mechanism by observing its operation. The same applies for semi-autos like the 1911, P226, and P250.

Pick up a Glock, Springfield XD, S&W M&P, or any number of other pistols with pre-tensioned strikers. Pull the triggers and you can't categorize the trigger mechanisms because there is no readily observable difference. Except for some value of theoretical knowledge, the classification of the trigger mechanism has no real utility for a user.
 

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Well, an "uncharged" condition is pretty uncommon for the SIG P320. When you load the pistol by inserting a loaded magazine and cycling the slide, the striker has been "charged" by the slide cycling.

When you reload by inserting a fresh magazine and releasing the slide, the striker has also been charged when the slide cycled back before it locked.

One real life instance in which the P320 striker might be "uncharged" is the event of a light primer strike. If you release the striker by pulling the trigger and the round in the chamber does not go bang, the striker tension has already been released and the striker has not been retensioned by the slide. In that event if you pull the trigger a second time, nothing will happen. The SIG P320 does not have "second strike" capability.

The slide does not need to come back very far to tension the striker. You can prove this by dry firing the pistol. If you cycle the slide and dry fire, the striker is released in the normal fashion. If you pull the trigger again, you will have a somewhat lighter trigger pull and you will hear a click. That click is the sear releasing again but the sear will not have captured the striker because the striker wasn't reset. The sear reset on the P320 is accomplished by the trigger pull, not the slide cycling.

If you dry fire and then pull the slide back about 3/4" or so, the striker will be retensioned and you can dry fire again normally and experience the regular trigger pull.
 

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Perhaps they just need to be referenced as striker fired...? Is the industry still trying use terminology from an era that doesn't have a very good application to striker fired technology? SF, without any attempt at DA or SA designation?
 

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IMO, to be a "True DAO", it would have to be a hammer-fired design.
Some striker-fired pistols (Glock for instance) can be manipulated to "simulate" a DAO gun.
P320 is 95+% charged when in battery, so it doesn't lend itself to this manipulation.
 

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I have seen Sig P320 carrys advertised as DAO. Thinking this might be unique to certain models or variations, I called Sig to find out. It took the rep 15 minutes to try to figure out what it was and never came up with a suitable answer. The info on this forum seems to be the most accurate I have come across. Thanks guys.
 

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I have seen Sig P320 carrys advertised as DAO. Thinking this might be unique to certain models or variations, I called Sig to find out. It took the rep 15 minutes to try to figure out what it was and never came up with a suitable answer. The info on this forum seems to be the most accurate I have come across. Thanks guys.
I do believe that SIG would like to reserve the option of calling a P320 DAO to help their chances at certain types of "bulk sales".
IMO the best description is P320 is a striker-fired pistol with the striker spring 95+% charged when in battery.
 

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I thought a striker-fire gun was an SAO gun with an internal hammer. That is why I bought a P320 because it was advertised that way and it works that way, which is what I wanted. The P320 as a DAO? I don't think so.
 

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I thought a striker-fire gun was an SAO gun with an internal hammer. That is why I bought a P320 because it was advertised that way and it works that way, which is what I wanted. The P320 as a DAO? I don't think so.
Technically (IMO) it is closer to a DAO than an SAO.
However it is actually neither.

SAO is off the table right off the bat, because there is no hammer.
Show me a SAO handgun that has no hammer.
There may be some obscure exception, but you get my drift.
 

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Is the p320 a true double action only where the trigger is the only thing that cocks the striker?
No it is striker fired.

If it were double action you could keep squeezing the trigger To practice dry firing without racking the slide.

This pistol requires the slide to travel reward to partially cock the striker, and since it is only partially cocked it is also not a single action.

The trigger finishes the cocking motion before releasing the striker.

That is why you have to move the slide reward between trigger pulls.

It is striker fired.
 
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