Recently a Member posted the eternal question: are Glock pistols are Single Action or Double Action? Well, maybe it's not THE eternal question, but it's one we hear regularly. I gave the question some thought and decided to measure the striker travel. Maybe knowing something about that would help me to accurately describe the Glock trigger action in terms that most shooters would understand.
To review, typically in a Single-Action semi-auto pistol, pulling the trigger pushes against a sear, which in turn releases the hammer to fire the weapon. The hammer is cocked independently of the trigger, typically by cycling the slide, but it may also be cocked manually in most cases. Familiar examples of Single Action semi-auto pistols include the 1911 and the Browning Hi Power.
Typically, in a Double-Action semi-auto pistol, pulling the trigger on the first shot (when the hammer is in the fired position) first cocks the hammer and then releases it to fire the weapon. On subsequent shots, the pistol fires in Single-Action, since it is cocked by the cycling of the slide. Examples of Single Action/Double Action (SA/DA) pistols include the CZ 75, most Sig Semi-Autos, the Walther PP, HK P2000, and the Beretta 92FS. The most common DA only (DAO) pistol I can think of is the Ruger LC9, and there are Sig variants that are DAO.
Where does Glock fit? Well, somewhere in between the two, actually.
As we know, when the Glock slide is cycled, it partially cocks the striker spring by pushing the nose of the striker against the (temporarily) stationery trigger bar cruciform. Pulling the trigger back further cocks the striker by pushing back on the nose of the striker until the trigger bar is pushed down by the connector to release the striker, and the pistol fires.
The nose of the striker has three positions when correctly installed in the pistol:
1. Fired, fully forward
2. Partially cocked, when the slide is cycled
3. Fully cocked, just before firing, when the trigger is pulled all the way back
I was able to measure the travel distance of the striker nose (and therefore the entire striker) by using the Orange Half-Height slide cover plate, used for inspection only. For the curious, this is part number SP 05865, and is readily available from Glock aftermarket suppliers.
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Using this cover plate allowed me to insert a caliper with a depth gauge attachment into the back of the pistol, noting the depth from the back of the cover plate to the back of the nose of the striker.
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Here are the measurements:
1. Fired, fully forward: .726"
2. Partially cocked, when the slide is cycled: .405"
3. Fully cocked, the rearmost position of the striker: .270"
Please note that these measurements are approximate, I did not use a fixture to hold the caliper or the pistol in place, and my hands probably shake a little.
So, what does all of this tell us?
1. Cycling the slide cocks the striker .321"
2. Pulling the trigger cocks the striker the final .135"
Total travel of the striker is .456". Since 70% (.321") of the travel occurs during cycling of the slide, and only 30% (.135") occurs during the trigger pull, it seems fair to me to describe the Glock as a Single Action Biased, striker-fired pistol.
Of course, others will differ!
To see this in action, here's that excellent Glock animation again: Glock Pistol Animation
Chris
To review, typically in a Single-Action semi-auto pistol, pulling the trigger pushes against a sear, which in turn releases the hammer to fire the weapon. The hammer is cocked independently of the trigger, typically by cycling the slide, but it may also be cocked manually in most cases. Familiar examples of Single Action semi-auto pistols include the 1911 and the Browning Hi Power.
Typically, in a Double-Action semi-auto pistol, pulling the trigger on the first shot (when the hammer is in the fired position) first cocks the hammer and then releases it to fire the weapon. On subsequent shots, the pistol fires in Single-Action, since it is cocked by the cycling of the slide. Examples of Single Action/Double Action (SA/DA) pistols include the CZ 75, most Sig Semi-Autos, the Walther PP, HK P2000, and the Beretta 92FS. The most common DA only (DAO) pistol I can think of is the Ruger LC9, and there are Sig variants that are DAO.
Where does Glock fit? Well, somewhere in between the two, actually.
As we know, when the Glock slide is cycled, it partially cocks the striker spring by pushing the nose of the striker against the (temporarily) stationery trigger bar cruciform. Pulling the trigger back further cocks the striker by pushing back on the nose of the striker until the trigger bar is pushed down by the connector to release the striker, and the pistol fires.
The nose of the striker has three positions when correctly installed in the pistol:
1. Fired, fully forward
2. Partially cocked, when the slide is cycled
3. Fully cocked, just before firing, when the trigger is pulled all the way back
I was able to measure the travel distance of the striker nose (and therefore the entire striker) by using the Orange Half-Height slide cover plate, used for inspection only. For the curious, this is part number SP 05865, and is readily available from Glock aftermarket suppliers.
Using this cover plate allowed me to insert a caliper with a depth gauge attachment into the back of the pistol, noting the depth from the back of the cover plate to the back of the nose of the striker.
Here are the measurements:
1. Fired, fully forward: .726"
2. Partially cocked, when the slide is cycled: .405"
3. Fully cocked, the rearmost position of the striker: .270"
Please note that these measurements are approximate, I did not use a fixture to hold the caliper or the pistol in place, and my hands probably shake a little.
So, what does all of this tell us?
1. Cycling the slide cocks the striker .321"
2. Pulling the trigger cocks the striker the final .135"
Total travel of the striker is .456". Since 70% (.321") of the travel occurs during cycling of the slide, and only 30% (.135") occurs during the trigger pull, it seems fair to me to describe the Glock as a Single Action Biased, striker-fired pistol.
Of course, others will differ!
To see this in action, here's that excellent Glock animation again: Glock Pistol Animation
Chris
