da/sa pistols

Question
QUESTION: I understand the term sa  "single action" pistol, ie. the hammer is cocked when the slide is 'manually' retracted and the pull on the trigger releases the cocked hammer on the first shot as it does on all subsequent shots. All subsequent cockings of the hammer are accomplished by the 'automatic retraction' of the slide produced by the explosion of the first cartridge. THE TRIGGER DOES NOT COCK THE HAMMER.

My question, and I have not been able to get a satisfactory answer either on the web or from quite knowledgeable people, is: why, when manually retracting the slide on a da/sa pistol (also referred to as da pistol} does the pull of the trigger on the first shot "cock the hammer" in addition to releasing it?

I came up with an answer that makes sense to me and may be the correct answer. I noticed that on the "da" pistols I am familiar with they all have a decocking lever.  Is decocking the hammer resulting in the trigger performing two functions on the first shot what makes the pistol a DA/SA pistol?  Would da pistols perform as sa pistols if the hammer were not decocked on the first shot?  If so, that raises another question. If a cartridge on a sa pistol such as a colt 1911 were manually chambered by the slide and the hammer was manually "decocked", maybe not a good idea, would the pull of the trigger be able to "cock"  and release the hammer thus turning these sa pistols into da pistols or what the design of these guns prevent this?

PLEASE, PROVIDE AN ANSWER I CAN UNDERSTAND!!!!!!!!  SO FAR, IT DOESN'T MAKE ANY SENSE TO ME HOW THE RETRACTION OF THE SLIDE, WHETHER MANUALLY OR AUTOMATICALLY, CAN MAKE ANY DIFFERENCE as to how the trigger functions on the first shot.

Help,   Alan


ANSWER: Guns are pretty simple tools. Probably the best way for you to understand them is to get hold a specimen of the gun you are interested in. You might even consider getting the gunsmithing videos of AGI which will show you in detail how they work. The difficulty you've had in obtaining a satisfactory answer so far is probably due to the fact that those who are giving you an answer are picturing the mechanism in their head, and trying to put into words something that you don't have a point of reference for.

Simply as I can put it:

1) On a single-action pistol, such as the 1911, when the slide is retracted it of course pushes the hammer back out of the way. The hammer hooks are engaged by sear. When the trigger is pulled, the sear is tripped and it lets the hammer fall. One the hammer is down, it needs to be reengaged by the sear to fire again. Therefore, manually lowering the hammer would simply disengage the sear from the hammer hooks - so no, pulling the trigger would not cock the hammer - there is no mechanism in the gun to do that - the trigger does one thing - move the sear out of the way so the hammer can fall.

2)On a DA action pistol (such as a Beretta or SIG) the trigger has additional linkage in it. Pull the trigger actually levers the hammer back to the end of its travel and then allows it to fall. Once the slide is retracted, however, it engages another mechanism in the gun (the single action sear), and from that point on the trigger simply releases the sear. If the gun is decocked (mechanically, either the firing pin is moved out of the way [Beretta] or the decocking action does not allow the hammer to strike the firing pin [SIG]), if the trigger is pulled, it then utilized the double action sear to lever the hammer back and let it drop.

---------- FOLLOW-UP ----------

QUESTION: Thanks for your reply,

From your explanation,?I understand operation of the single action pistol; however, the operation of the da pistol is somewhat still unclear.

I now know that there is an 'additional mechanism' in a da pistol which is activated by the manual?movement of the slide on the first shot and permits the pull of the trigger to both cock the hammer and release it thus firing the chambered cartridge. Thereafter,?the sear which only releases the cocked hammer is active,?the hammer being cocked by the recoil movement of the slide from the discharged cartridge.

That being the case, if we load an ammunition free da pistol and manually retract the slide and release it, the slide will pick up and chamber a cartridge from the clip. It would follow that, if I understand you correctly, the initial 'manually' action of the slide chambering a cartridge must somehow not cock the hammer as it does in a sa pistol. ?If that gun had a visible hammer it should appear uncocked. The activated?"additional mechanism"?lets the pull of the trigger both cock the hammer and release it thus firing the gun on the shot.?I understand that AFTER the first shot the recoil of the slide cocks the hammer,?the additional mechanism is inactive, and the pull of the trigger functions as it does in a sa?gun - just releasing the hammer on all subsequent shots.

If my reasoning is correct, the question is: is there a third function to the additional mechanism you mentioned or any additional mechanism which prevents the hammer from being cocked during the manual operation of the slide while chambering the FIRST BULLET??You state that on the first shot the 'additional mechanism' cocks and release the hammer.?As you can see only one thing needs to be cleared up. What prevents the hammer from being cocked on the chambering of the first bullet??Is it a third function of the 'additional' mechanism which you forgot to mention??

How can you put up with guys like me?

Regards,牋 Alan

Answer
You assumption is incorrect.

If you chamber a round on a DA pistol (either by reciprocating the slide, or closing a locked slide), the hammer will be cocked, and the gun will fire in the single action mode.

In order to use the DA firing mechanism, after chambering a round, you have to decock the gun, which is accomplished by the aforementioned mechanisms that will lower the hammer without firing the gun. After that, the gun is fired for the first round double action, for all subsequent rounds single action unless the gun is decocked.

The sequence, then, is:

1) To load, insert magazine, reciprocate slide, to chamber around (leaving you with a cocked hammer).

2) Decock hammer. Now the gun is ready to be fired in the double action mode.

3) After the first shot (DA), all other subsequent shots will be SA until the gun is manually docked (or runs out of ammunition)