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  #1  
Old 02-13-2013, 04:32 PM
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Smile m&p 9mm double action only

what is meant by the "double action only" statement on the m&p 9mm full size semi automatic without manual thumb safety? and the one that has a manual thumb safety doesn't have this listed that way. Is there some internal differences between the two?

Last edited by Ray F; 02-13-2013 at 05:04 PM.
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Old 02-13-2013, 05:18 PM
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The modern "safe action" gun designs kind of blur the S/A-D/A description. The M&P releases the striker when the trigger is pulled so I would consider it a S/A with a long pull. Some of the striker-fired guns do actually pull the striker further to the rear before release so in effect they would be a DAO I guess. To me the striker-fired guns just don't clearly fall into either class.
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Old 02-13-2013, 05:43 PM
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Default m&p 9mm double action only

To answer ray f's question:

There is no difference internally between the two firearms (other than the presence of the safety selected switch). If you picture a revolver- you can either puller the hammer back manually then pull the trigger to fire the weapon (single action), or you can simply pull the trigger to fire the weapon (double action). As with the M&P, there is no hammer to pull back; therefore simply pulling the trigger is the only way to fire the weapon. This is my understanding of the whole single action double action thing. I could be way wrong. Hope this helps.
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Old 02-13-2013, 07:00 PM
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With or without the safety, the trigger action to striker release is the same in both M&P models. The safety just prevents the trigger from moving. Just the way S&W wants to describe the action. Maybe S&W feels the terminology of "double action" sounds safer to some people.

For all practical purposes the M&P's are single action. But S&W calls them double action (see the reason below). Understand one action and the hammer/striker drops while double action requires two actions for the hammer/striker to drop. As explained in a prior post most revolvers can be both.

A single action revolver is when the hammer has been manually cocked. By pulling the trigger, the hammer is dropped. This only required one action to drop the hammer, just pulling the trigger. Normally in a single action revolver trigger pull, the trigger pull length is very short. A double action in a revolver is when the hammer is down. The trigger pull causes the hammer to move back, and normally causes the cylinder to rotate. By continuing pulling the trigger back, the hammer will drop. This is double action because the first action of pulling the trigger caused the hammer to move back, and the further pulling of the trigger caused the second action, the hammer drop. The double action trigger pull length is normally much longer than the single action trigger pull.

In a single action pistol, the trigger pull causes the hammer/striker to fall. However why S&W calls this double action is due to the fact the sear on all M&P pistols, has a slight raised "bump" on the sear face. With the trigger pull, as the sear moves down, the bump contacts the striker and the bump pushes the striker rearward about 1/32 inch. Since the trigger pull is doing two actions, moving the striker rearward (1/32 inch) and causing the striker to release (drop), this is two actions or double action. It is a very trivial reason to call it double action, for 1/32 inch of striker movement, but it is double action.

A true double action pistol would be similar to my Ruger LC9 and many other double action pistols. The trigger pull causes the hammer to move back (cocking the hammer) and by continuing to pull the trigger the hammer will drop.

My Shield 40 had the bump on the sear. But when I replaced the sear with an Apex sear, which does not have the bump on the sear, I made my Shield go from double action to single action. Not really as the M&P's are actually single action (sorry S&W but it is not a true double action), with a tiny bit of striker rearward movement.

Bob

Last edited by robkarrob; 02-13-2013 at 07:29 PM.
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Old 02-13-2013, 07:26 PM
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Quote:
Originally Posted by robkarrob View Post
A true double action pistol would be similar to my Ruger LC9 and many other double action pistols. The trigger pull causes the hammer to move back (cocking the hammer) and by continuing to pull the trigger the hammer will drop.
Well...this is where I get tangled up in terminology. For instance...on my wife's LC9, and I assume yours as well, the hammer is at least partially cocked by the action of the slide. Pulling the trigger makes the hammer go all the way back and then releases it. If the round doesn't fire, you can't pull the trigger again...no second strike ability...you have to cycle the slide again. So, to me, it isn't a true DA pistol.

When I think of a true DA action, I think of it being like a DA revolver. There are a few semi-automatics which have 2nd strike capability, so I think of them as true DA action as well.

It gets confusing...or maybe it's just me.
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Old 02-13-2013, 10:14 PM
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GKC reply


The LC9 is a true double action (DA). The hammer starts at half way back. The trigger pull causes the hammer to move fully rearward and then the hammer drops. The Sig Sauer P220 is a DA/SA, similar to a revolver. The hammer is exposed and can be pulled back for the single action. Or if the hammer is lowered the trigger pull will cock the hammer, like a revolver. Once the gun is fired the slide cocks the hammer and it operates as SA. You mention double strike. These guns are DA as the trigger pulls the hammer or striker back, similar as the Sig pulls the hammer back in DA. If the Sig did not fire the first time, by pulling the trigger again, it would re-cock the hammer and drop it again, for a double strike capability.

The terminology is simple. If the pull of the trigger does only one thing, drops the hammer/striker, it is SA. If the pull of the trigger does more than one thing, cocks the hammer/striker and then drops the hammer/striker, it is considered DA.

Bob

Last edited by robkarrob; 02-13-2013 at 10:21 PM.
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Old 02-13-2013, 11:42 PM
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The terminology is simple. If the pull of the trigger does only one thing, drops the hammer/striker, it is SA. If the pull of the trigger does more than one thing, cocks the hammer/striker and then drops the hammer/striker, it is considered DA.

Bob
That helps. Thanks.
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Old 02-14-2013, 05:01 AM
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The Chairborne Rangers who select firearms for large departments (or even small ones) are leery of Single Action firearms....

SO, manufacturers try....

The M&P's are nominally SA, but there's no current "code" for it, so DAO or something like "Safe Action" is used....

One of the funniest is, IMHO, Para Ordnance's LDA guns. "Light Double Action". In truth, they're as Single Action as anybody else's 1911, except that the trigger does move the hammer back to firing position like a DA gun. Problem is that it's about 2# to get to the firing position (with the usual 5#-ish trigger), so there's little real value except if you're transitioning to an LDA from a wheelgun.

But the Para guns don't look as aggressive .... The hammer is down.... (Now that Para's using a very flat hammer in their LDA guns, you can use Condition One leather - a top strap under the hammer - with the LDA's. You just put the top strap over the hammer. Convenient....)

Couple of other definitions: SA/DA (or "Traditional" DA), where the first shot can be SA or DA, depending on the user's preferences. (I.e., cock the hammer if you want to.) DAO (Double Action Only) just presumes that you can't cock the hammer manually. Both of these may have double-strike capabilities. (The Para LDA's DO NOT.) Just me, but a second strike may be a waste of time in modern ammunition....

Buy several of each!

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Old 02-14-2013, 02:05 PM
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Guns of this type are also often referred to as "striker fired" indicating that thy are neither single action nor double action, as they terms have traditionally been used. I admit to having been confused when I first started shopping for my first semi-auto, and saw reviewers referring to th M&P as SA by some and DA by others, so I appreciate your question. It is seething of a unique category, and I think is even distinguishable from a Glock ( which I have never shot) given the Glock "safe trigger".
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Old 02-14-2013, 05:56 PM
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bobermo reply

M&P's have internal strikers, not hammers, and can not be cocked with the trigger. The only way to cock the striker is to rack the slide and on the forward movement of the slide, the striker is cocked. No the chamber cannot be loaded and uncocked. When the slide is racked back, the striker is cocked when the slide returns forward. It could be carried uncocked with an empty chamber if the trigger is pulled to release the striker, on an empty chamber.

The SA/DA guns like the Sig have a problem. If pulling the trigger with the hammer down (DA), the trigger pull is very long and a much heavier pull to break. Then the gun works as a SA with a very short and much lighter pull. This means you have to adjust to two different types of trigger pulls in one gun. No a good situation. The SA guns, which the M&P's really are, have only one trigger pull that you have to adjust to, which makes the gun much more suitable for a SD gun. No long pull, short pull to mess you up. The M&P's have the same pull each and every time.

Bob
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Old 02-14-2013, 06:46 PM
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Default m&p 9mm double action only

Ya my Sig 228 is DA and if there is a round in the chamber and the hammer is down(uncocked), the trigger pull is MUCH heavier on the DA mode first round, as to where the slide cocks the hammer each cycle making it SA and a very light trigger. Trying to learn the whole DA/SA thing when asking about my Sig was very confusing as it's technically both
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Old 02-14-2013, 07:09 PM
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Quote:
Originally Posted by bobermo View Post
Forgive my ignorance on this subject, as I have not handled a m&p 9mm but in the market for one.

Can you cock the hammer using the trigger, since it can not be cocked with your thump like a sig. The sig seems like a true DA. You can cock the hammer using the trigger. You can chamber a round by pulling the slide, then manually release the hammer. Now you have a loaded weapon ready to fire with just a long pull of the trigger.

For m&p 9, can the chamber be loaded without a cocked hammer/striker? For example, can it be carried uncocked with a loaded chamber? I take it there is no way to uncock the hammer/striker after pulling the slide to load a round like with the sig.

Just curiuos if it's safe to carry the m&p with a round in the chamber with a cocked hammer/striker without the thumb safety. If the striker needs to move backwards slightly before before disengaging from the sear, it helps prevent misfires from jolts and bumps.
Here's a video posted by robkarrob that may help you understand the stiker-fire system and how it works.

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Old 02-14-2013, 08:52 PM
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Default m&p 9mm double action only

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I can see your point. Is it safe to keep the sig in SA mode (hammer cocked) when carrying or is that not advised?
Umm, honestly I'd be lying if I said. I don't know. I don't carry it, but I do use it as one of my HD weapons so I leave one in the chamber and uncocked. In case of emergency I'll still be able to pull the trigger, but for some reason I prefer to leave it uncocked. Whether this is right or not I couldn't say
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Old 10-22-2013, 12:25 AM
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Thinking about upgrading to the M&P 9mm from my M&P .22lr but the S&W website says the 9mm M&P's are double action only that is throwing me off. From what I understand from the above posts is the
9mm is the same as the .22lr rack the slide and fire right? That's what I'm used to and that's what I want to stick with. So the 9mm is still a single action right?
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Old 10-22-2013, 12:56 AM
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Originally Posted by PennGrizz View Post
Thinking about upgrading to the M&P 9mm from my M&P .22lr but the S&W website says the 9mm M&P's are double action only that is throwing me off. From what I understand from the above posts is the
9mm is the same as the .22lr rack the slide and fire right? That's what I'm used to and that's what I want to stick with. So the 9mm is still a single action right?
Yes, you rack the slide and fire the M&P 9mm. The discussion/argument about single and double action is one I won't get into
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Old 10-22-2013, 05:06 AM
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They are technically single action due to how the stock trigger system works, but called a double for the same reason... Makes sense?

Basically in stock form the gun feels like a double but really acts like a single.

The reason is what happens during trigger pull. The trigger feels like a double, you get a nice long long pull and stack up of trigger force before release which is similar to a double action . This happens because as you squeeze the trigger the sear is rotating and pushing the striker pin back before it is released leading to a stack up.

But it really is single... You have no ability to decock the striker and even if you some how managed that squeezing the trigger does not reengage the striker for firing.

So why called a DAO? So it appeals to LE and because it feels like it...

An APEX DCAEK kit replaces the sear so that you eliminate that stack up during trigger pull and just get a clean break like a SA with a nice light 5lbs or so trigger force while still being good for a carry application. APEX also offers trigger kits that reduce the trigger stroke before and after break to make it feel ever more like a SA.

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Old 10-22-2013, 01:42 PM
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[QUOTE=
You have no ability to decock the striker and even if you some how managed that squeezing the trigger does not reengage the striker for firing.

Sent from my SCH-I605 using Tapatalk[/QUOTE]

Does that mean the pistol has to be fired if you chamber a round??
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Old 10-22-2013, 02:21 PM
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Does that mean the pistol has to be fired if you chamber a round??
or unloaded
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Old 10-22-2013, 02:23 PM
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If a round is chambered the pistol is live. Even without a round chambered the striker is engaged and ready to release, unless you pull the trigger. There is no way to disengage the striker with a loaded chamber.

Not to worry though. The striker safety system has multiple controls and in an unmolested m&p no way for the striker to release unless you pull the trigger

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Old 10-22-2013, 03:05 PM
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Originally Posted by PennGrizz View Post
Does that mean the pistol has to be fired if you chamber a round??
It's not necessary to fire a round after chambering it:
Drop the mag and then rack the slide to eject the chambered round, and the pistol is as unloaded as any pistol ever gets ("Always treat any gun as if it were loaded and ready to fire").

If you lock the slide open, the pistol is also 'decocked' (the striker is not pulled back.) Whenever the slide goes forward, the striker is cocked, regardless of if there is a round chambered or not, & remains that way until either the trigger is pulled or the slide is again racked back.
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Old 12-23-2013, 12:21 PM
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Hey guys! My first post, so please forgive my forum ignorance: With all of this talk whether or not the m&p9 is SA or DA, is it at all possible to convert the gun to true DA. If so, what is the feasibility of doing so. Thanks in advance!
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Old 12-23-2013, 02:04 PM
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BTMAQ:

No....

It's really more or less an SA.... The DA view (IMHO) is because moving the sear moves the striker just a little bit before releasing it.

Essentially, otherwise, it's an SA. The striker is held back (cocked) when the slide goes forward with a chambered round most of the time. You can interfere with that by not getting a trigger reset, but that's another story.

Converting the gun to a true DA would require a significant redesign of the trigger mechanism - you'd have to draw back the striker some distance, and the existing setup really doesn't let the trigger mechanism near the striker. All it does is nudge the sear and move the drop safety plunger out of the way.

KelTec's .380 and 9mm (at least the ones I've played with) use a real hammer, and in that sense are DAO because the trigger mechanism draws the hammer back for you. The P3AT leaves the hammer down after firing, but there's a reset while the slide is going backwards, that moves the hammer back a quarter-inch or so. It doesn't stay fully back....

I've got a couple of Para LDA guns (1911's). The trigger does move the hammer back, like a DA design, but once a round has been chambered, the gun's really an SA that just happens to need to have it's hammer moved back to the "fire" position. About 2# of pressure is needed v.s. the much heavier pull for a DA revolver. Calling it "DA" is really just marketing. IMHO, they could have designed it without the external hammer, but chose to stick with more or less an ordinary 1911 slide. I'm not sure about the drop safety, but I think only one simple machining cut would make an LDA slide work on a standard SA frame. Can't easily go the other way, though - the LDA slide needs a bit more machine work.

Oh yes... Welcome Aboard!

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Old 12-23-2013, 03:27 PM
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Quote:
Originally Posted by had2 View Post
Guns of this type are also often referred to as "striker fired" indicating that thy are neither single action nor double action,...
This is a misnomer. The fact that it has a striker instead of a firing pin has nothing to do with the type of action it is.

Quote:
Originally Posted by Dikinalaska View Post
Ya my Sig 228 is DA and if there is a round in the chamber and the hammer is down(uncocked), the trigger pull is MUCH heavier on the DA mode first round, as to where the slide cocks the hammer each cycle making it SA and a very light trigger. Trying to learn the whole DA/SA thing when asking about my Sig was very confusing as it's technically both
Not just technically, it is both a DA and a SA.

Quote:
Originally Posted by BTMAQ View Post
Hey guys! My first post, so please forgive my forum ignorance: With all of this talk whether or not the m&p9 is SA or DA, is it at all possible to convert the gun to true DA. If so, what is the feasibility of doing so. Thanks in advance!
The M&P cannot be converted to DA. This will become clear in a second...

The type of pistol action relates ONLY to the trigger and what it does.
Single Action(SA)- The trigger only releases the hammer or striker.
Double Action(DA)- The trigger cocks AND releases the hammer or striker.
DA/SA- The first pull of the trigger is DA and then the hammer is cocked by the movement of the slide so, subsequent pulls will be SA.

A DA/SA pistol could be carried cocked, but that is not considered safe.
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Old 12-23-2013, 04:32 PM
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The only way to cock a M&P or Glock or similar striker fire pistols is to rack the slide to charge the chamber with a round. This makes the gun ready to fire in all respects (providing there's no thumb safety). There is no hammer to manually pull back like on a 1911 type pistol. With a double action semi-auto pistol pulling the trigger will fire the gun, hammer cocked or not - DA/SA. When the first round is fired the slide will come back, charging a round in the chamber & cocking the gun. From then on until a mag change after the last round is fired the trigger pull will be shorter & lighter. With a single action only like say a cowboy type revolver like the Peacemaker the only way you can fire the gun is to pull the hammer back for each shot.
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