National Carry AcademyDouble Action/Single Action (DA/SA)
July 25, 2016
There is a particular type of trigger found on the Beretta M9, the Sig 226 and 232, the Taurus, the Beretta 92 and Px4 Storm, and other semi-automatic DA/SA pistols. The first shot can be double action or single action, depending on if the trigger is pressed initially for double action or if the hammer is manually cocked back with the thumb for single action, but one press of the trigger does cock and release the hammer if it is not cocked manually. If the hammer is manually cocked, the pressing of the trigger will release the hammer.
With the M9, for example, as a semi-automatic DA/SA pistol, the slide will re-cock the hammer after the gun is fired. With a DA/SA type of gun, all subsequent shots after the first DA press will be fired single action until shooting stops and the hammer is de-cocked. A DA/SA gun is always ready to fire as soon as the trigger is pressed with no need to disengage a safety. A concern (not insurmountable) that I have with my DA/SA guns is the hard first press of somewhere between 8-12 pounds (DA), but you can train to overcome it. My biggest concern with my DA/SA pistols is making the transition from the first long and hard press in double action to the second shot which is the short and soft single action press (ranges from 4 to 6 pounds or so.) There is a notable difference that we sometimes do not focus on in the “heat of battle.” I learned this in one of my first IDPA matches. Some even call the first DA shot a throwaway because there is so much movement with the first hard press that misses or off bullseye hits regularly occur… unless you practice and train for it. So I have found for me that my DA/SA pistols are harder to shoot well compared to my SAO, DAO, and striker-fired guns. I guess I just don’t want to dedicate extensive practice time with my DA/SA pistols, because I enjoy my others so much more. A personal preference thing. DA/SA guns have versatile mechanisms, are very shootable with proper instruction and training, and are great for teaching and learning trigger control. With the DA/SA gun, you must remember to safely decock it when you are not ready to fire. Holstering without decocking it first is very dangerous. I decock whenever my gun comes off target with no immediately obvious target to engage next. SAFETY FIRST. This is a step not necessary for SAO/DAO/Striker-Fired guns.
Striker Fired/Partially Cocked (SF)
SF guns strictly speaking are neither DAO nor SAO trigger mechanisms. They are striker fired, with their own system, trigger safeties and striker blocks, etc. For me, they offer a good balance of press weight, trigger travel, safety, and consistency. In SF pistols, the trigger engages the firing pin (which is part of and at the end of the striker) directly through a linkage called a striker trigger bar rather than by engaging and releasing a hammer to fall against the firing pin, as in hammer-fired guns. So, SF guns do not have a hammer or a separate firing pin. As the trigger is pulled the striker bar is drawn reward and eventually released. The end of the striker acts as a firing pin and strikes the primer, firing the gun. There is a sub-category of SF pistols in which the striker bar is left in a partially retracted position, after each shot, in order to make the trigger pull lighter. Glocks, M&Ps and XDs are in this category. The slide does about half the work of cocking the striker and then the trigger completes the other half of the cocking action and then releases the striker. Generally per my armorer friends, Glock’s striker must be retracted further than those of the M&P and XD in order to be released to come forward to fire a cartridge.
Another sub-category of SF pistols releases all striker energy returning the striker to a fully at rest position, so that it is not under spring tension. So many SF pistols are “pre-cocked” by slide action. The cocking can be partial or fully cocked, depending on the design. My layman, non-gunsmith understanding is that pressing the trigger simply releases the striker if the SAO SF type OR finishes cocking and releases the striker bar if the DAO type. This latter type of DAO SF is what Glock calls its Safe Action. But recognize that SF guns are not a true DAO. Some say they really operate as a SAO because the slide must be moved backward in order to activate the striker and the shooter cannot press the trigger cocking and dropping the hammer as a pure DA would. Most SF guns (not all) lack a manual safety, so recognize that if you do not press the trigger, the gun will not fire. For example, the Ruger LC9s and variants of the M&P do have an external, manual safety. A primary SF disadvantage is that pressing the trigger a second time after a failure to fire will not re-strike the primer. Usually not an issue since loading the gun requires that the slide be retracted to preset the striker. The usual way to decock is to pull the trigger on typical SFs. Most SF pistols cannot be decocked, e.g. Glocks. To reduce tension, remove the magazine, check the chamber to ensure it is empty, and cautiously and safely press the trigger. Clearing a malfunction usually involves retracting the slide following our Tap, Rotate, Rack, Assess, Bang drill anyway. Examples of SF guns include: Sig 320 series; S&W M&P series; Springfield XD, XDm, XDs series; Ruger SR series & LC9s; Glocks; H&K VP9; FN FNS-9; Walther PPQ M2 (SAO) & P99 (DA/SA); Beretta APX; Kahr CT9. The H&K P7 and Walther PPQ series to me fit the SAO SF model. Note the Walther P99AS is a SF DA/SA model and the PPQ M2 is more like a SAO SF.
SF advantages include no external hammer to snag on things and consistent trigger press with same weight through all presses. Some consider the lack of an external safety on most SFs to be an advantage because fewer steps are involved, since the manual safety does not have to be disengaged. Others believe that there is a safety risk to carry a pistol without external safeties. Some desire the traditional hammer-fired guns, while others prefer the SF guns. These are very hotly-debated issues. What do you think?
Trigger Variants
Aside from understanding the 5 basic types of triggers, recognize there are some sub-type variants of actions and some unique triggers that exist. Variations like the Para LDA (Light Double Action), H&K LEM (Law Enforcement Modification), Sig Sauer DAK (Double Action Kellerman), etc. For example, the Sig DAK trigger system was developed by Sig Sauer engineers with the goal of having a safe, reliable and consistent 6.5 pound double-action-only (DAO) trigger press with double-strike capability and a short reset. When firing a DAK pistol, the first trigger pull is about 6.5 pounds of force (compared to about 12 pounds for the standard DAO). After the pistol fires and the trigger is released forward the trigger has an intermediate reset point that is approximately halfway to the trigger at rest position. The trigger pull from this intermediate reset point is heavier at about 8.5 pounds. If the trigger is released all the way forward, this will engage the primary trigger reset and have a trigger pull of 6.5 pounds. To engage the intermediate reset the trigger must be held to the rear while the slide is cycled, either manually or by the recoil of a round being fired. With the H&K LEM DAO trigger variant (e.g. my H&K P30 LEM, Light Version 1), you have a short, light, and consistent trigger press (about 4.5 pounds), after a long initial trigger travel but with a short reset and the same light trigger press each time. I love mine, but you have to practice and get use to it. Because DAK, LDA, and LEM triggers move all the way forward between shots IF you let them, you never run the risk of losing contact with the trigger between shots. To me this means much less chance of slapping the trigger when shooting fast. The LEM short reset and consistent light single-action-type press is impressive for me, IF I can get use to the longer trigger travel up front and taking up the slack. These are a few action variations, but there are others.
I hope this information has helped you better understand trigger actions and the many variations, so you can try them for yourself and make an optimal purchase decision and better operate your handguns.
This personal opinion article is meant for general information & educational purposes only and the author strongly recommends that you seek counsel from an attorney in your state or jurisdiction for legal advice and your own personal certified weapons trainer for proper guidance about shooting & using YOUR firearms, self-defense, stand your ground law, and concealed carry. This is not legal advice and not legal opinions. It should not be relied upon as accurate for all shooters & the author assumes no responsibility for anyone’s use of the information and shall not be liable for any improper or incorrect use of the information or any damages or injuries incurred whatsoever. Safety First!
Double Action/Single Action (DA/SA)
July 25, 2016
There is a particular type of trigger found on the Beretta M9, the Sig 226 and 232, the Taurus, the Beretta 92 and Px4 Storm, and other semi-automatic DA/SA pistols. The first shot can be double action or single action, depending on if the trigger is pressed initially for double action or if the hammer is manually cocked back with the thumb for single action, but one press of the trigger does cock and release the hammer if it is not cocked manually. If the hammer is manually cocked, the pressing of the trigger will release the hammer.
With the M9, for example, as a semi-automatic DA/SA pistol, the slide will re-cock the hammer after the gun is fired. With a DA/SA type of gun, all subsequent shots after the first DA press will be fired single action until shooting stops and the hammer is de-cocked. A DA/SA gun is always ready to fire as soon as the trigger is pressed with no need to disengage a safety. A concern (not insurmountable) that I have with my DA/SA guns is the hard first press of somewhere between 8-12 pounds (DA), but you can train to overcome it. My biggest concern with my DA/SA pistols is making the transition from the first long and hard press in double action to the second shot which is the short and soft single action press (ranges from 4 to 6 pounds or so.) There is a notable difference that we sometimes do not focus on in the “heat of battle.” I learned this in one of my first IDPA matches. Some even call the first DA shot a throwaway because there is so much movement with the first hard press that misses or off bullseye hits regularly occur… unless you practice and train for it. So I have found for me that my DA/SA pistols are harder to shoot well compared to my SAO, DAO, and striker-fired guns. I guess I just don’t want to dedicate extensive practice time with my DA/SA pistols, because I enjoy my others so much more. A personal preference thing. DA/SA guns have versatile mechanisms, are very shootable with proper instruction and training, and are great for teaching and learning trigger control. With the DA/SA gun, you must remember to safely decock it when you are not ready to fire. Holstering without decocking it first is very dangerous. I decock whenever my gun comes off target with no immediately obvious target to engage next. SAFETY FIRST. This is a step not necessary for SAO/DAO/Striker-Fired guns.
Striker Fired/Partially Cocked (SF)
SF guns strictly speaking are neither DAO nor SAO trigger mechanisms. They are striker fired, with their own system, trigger safeties and striker blocks, etc. For me, they offer a good balance of press weight, trigger travel, safety, and consistency. In SF pistols, the trigger engages the firing pin (which is part of and at the end of the striker) directly through a linkage called a striker trigger bar rather than by engaging and releasing a hammer to fall against the firing pin, as in hammer-fired guns. So, SF guns do not have a hammer or a separate firing pin. As the trigger is pulled the striker bar is drawn reward and eventually released. The end of the striker acts as a firing pin and strikes the primer, firing the gun. There is a sub-category of SF pistols in which the striker bar is left in a partially retracted position, after each shot, in order to make the trigger pull lighter. Glocks, M&Ps and XDs are in this category. The slide does about half the work of cocking the striker and then the trigger completes the other half of the cocking action and then releases the striker. Generally per my armorer friends, Glock’s striker must be retracted further than those of the M&P and XD in order to be released to come forward to fire a cartridge.
Another sub-category of SF pistols releases all striker energy returning the striker to a fully at rest position, so that it is not under spring tension. So many SF pistols are “pre-cocked” by slide action. The cocking can be partial or fully cocked, depending on the design. My layman, non-gunsmith understanding is that pressing the trigger simply releases the striker if the SAO SF type OR finishes cocking and releases the striker bar if the DAO type. This latter type of DAO SF is what Glock calls its Safe Action. But recognize that SF guns are not a true DAO. Some say they really operate as a SAO because the slide must be moved backward in order to activate the striker and the shooter cannot press the trigger cocking and dropping the hammer as a pure DA would. Most SF guns (not all) lack a manual safety, so recognize that if you do not press the trigger, the gun will not fire. For example, the Ruger LC9s and variants of the M&P do have an external, manual safety. A primary SF disadvantage is that pressing the trigger a second time after a failure to fire will not re-strike the primer. Usually not an issue since loading the gun requires that the slide be retracted to preset the striker. The usual way to decock is to pull the trigger on typical SFs. Most SF pistols cannot be decocked, e.g. Glocks. To reduce tension, remove the magazine, check the chamber to ensure it is empty, and cautiously and safely press the trigger. Clearing a malfunction usually involves retracting the slide following our Tap, Rotate, Rack, Assess, Bang drill anyway. Examples of SF guns include: Sig 320 series; S&W M&P series; Springfield XD, XDm, XDs series; Ruger SR series & LC9s; Glocks; H&K VP9; FN FNS-9; Walther PPQ M2 (SAO) & P99 (DA/SA); Beretta APX; Kahr CT9. The H&K P7 and Walther PPQ series to me fit the SAO SF model. Note the Walther P99AS is a SF DA/SA model and the PPQ M2 is more like a SAO SF.
SF advantages include no external hammer to snag on things and consistent trigger press with same weight through all presses. Some consider the lack of an external safety on most SFs to be an advantage because fewer steps are involved, since the manual safety does not have to be disengaged. Others believe that there is a safety risk to carry a pistol without external safeties. Some desire the traditional hammer-fired guns, while others prefer the SF guns. These are very hotly-debated issues. What do you think?
Trigger Variants
Aside from understanding the 5 basic types of triggers, recognize there are some sub-type variants of actions and some unique triggers that exist. Variations like the Para LDA (Light Double Action), H&K LEM (Law Enforcement Modification), Sig Sauer DAK (Double Action Kellerman), etc. For example, the Sig DAK trigger system was developed by Sig Sauer engineers with the goal of having a safe, reliable and consistent 6.5 pound double-action-only (DAO) trigger press with double-strike capability and a short reset. When firing a DAK pistol, the first trigger pull is about 6.5 pounds of force (compared to about 12 pounds for the standard DAO). After the pistol fires and the trigger is released forward the trigger has an intermediate reset point that is approximately halfway to the trigger at rest position. The trigger pull from this intermediate reset point is heavier at about 8.5 pounds. If the trigger is released all the way forward, this will engage the primary trigger reset and have a trigger pull of 6.5 pounds. To engage the intermediate reset the trigger must be held to the rear while the slide is cycled, either manually or by the recoil of a round being fired. With the H&K LEM DAO trigger variant (e.g. my H&K P30 LEM, Light Version 1), you have a short, light, and consistent trigger press (about 4.5 pounds), after a long initial trigger travel but with a short reset and the same light trigger press each time. I love mine, but you have to practice and get use to it. Because DAK, LDA, and LEM triggers move all the way forward between shots IF you let them, you never run the risk of losing contact with the trigger between shots. To me this means much less chance of slapping the trigger when shooting fast. The LEM short reset and consistent light single-action-type press is impressive for me, IF I can get use to the longer trigger travel up front and taking up the slack. These are a few action variations, but there are others.
I hope this information has helped you better understand trigger actions and the many variations, so you can try them for yourself and make an optimal purchase decision and better operate your handguns.
This personal opinion article is meant for general information & educational purposes only and the author strongly recommends that you seek counsel from an attorney in your state or jurisdiction for legal advice and your own personal certified weapons trainer for proper guidance about shooting & using YOUR firearms, self-defense, stand your ground law, and concealed carry. This is not legal advice and not legal opinions. It should not be relied upon as accurate for all shooters & the author assumes no responsibility for anyone’s use of the information and shall not be liable for any improper or incorrect use of the information or any damages or injuries incurred whatsoever. Safety First!