Question about hammer velocity

G

gbclarkson

New member
So I was watching a show titled Hollywood Weapons, or something like that title, the other night while trying to put myself to sleep. It was a Myth Busters-type show that tested the validity of shoot out scenes from action movies. This particular episode examined an action sequence in which the action hero's car gets completely submerged, the car's cabin is completely filled with water, and there is a bad guy on the other side of the windshield. I forget the name of the source movie. Anyway, action hero pulls his Glock 9mm and shoots bad guy through the windshield while underwater. The episode wanted to know if the bullet would have sufficient velocity to penetrate the windshield and the test dummy on the other side. It did not. Three 9mm rounds bounced off the test glass. Though, it looked as if the show's host was several feet behind the underwater windshield and not actual front seat-to-windshield distance. Distance is difficult to judge on TV.

They repeated the test with a .357 magnum GP 100, which also did not penetrate the windshield, and then a .454 Casull Ruger Alaskan which went right through. The revolvers were experiencing a 50% ignition rate. They theorized that water resistance was slowing the hammer and causing light primer strikes. Their solution was to fire the revolvers in single action mode to speed up the hammers. This got me pondering: Is the terminal velocity of the hammer faster when firing single action? Is the rearward distance of the hammer also greater when firing single action?

Is there a practical application to this knowledge? Would rimfire revolvers fire more reliably in SA?
 
Shooting most guns single action does result in a longer arc for the hammer to travel and allows it to pick up more speed. You can experiment with the hammer springs and in a GP100 and have a gun that is 100% reliable in single action and 90% reliable in double action. I'm not sure what the practical application would be because I'd prefer all my guns to function both SA and DA.
 
reddog81 said:
Shooting most guns single action does result in a longer arc for the hammer to travel and allows it to pick up more speed. You can experiment with the hammer springs and in a GP100 and have a gun that is 100% reliable in single action and 90% reliable in double action. I'm not sure what the practical application would be because I'd prefer all my guns to function both SA and DA.
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I have come to the realization that I do not care for any handgun that lacks a hammer, semi-auto or revolver.

I tried a couple of DAO revolvers...no hammers...and did not like them at all.
Sometimes a single action shot is desired...and I want the option.
Gary
 
Howdy

With every double action revolver that I have ever seen, the hammer goes back more when cocked single action than double action.

Here is how it works in a Smith and Wesson. This is a Model 14-3. The hammer block has been removed so things can be seen more clearly. The upper arrow is pointing to the Double Action Sear. This is a spring loaded lever. The lower arrow is pointing to the area where all the cocking business happens.

Model%2014-3%20Hammer%20Down%20with%20Arrows_zpso0yvbukg.jpg





In this close up, the lower arrow is pointing to the single action cocking notch on the hammer. The upper arrow is pointing to the part of the trigger that will cam the hammer backwards when the trigger is pulled double action. As the trigger is pulled, it engages the Double Action Sear, levering the hammer back. At a predetermined angle, the trigger will slip past the Double Action Sear allowing the hammer will fall.

Model%2014-3%20Hammer%20Down%20Closeup%20with%20Arrows_zpsk3vp1xby.jpg





When shooting in single action mode, the Double Action Sear does not enter into the action. Instead, the part of the hammer under the trigger will rock the trigger back.

Model%2014-3%20Hammer%20Cocked_zpsa1kplnh3.jpg





As the hammer rocks back all the way, the trigger will pop into the tiny single action cocking notch on the hammer. When the trigger is depressed, it pops out of the notch and the hammer falls.

Model%2014-3%20Hammer%20Cocked%20Closeup%20with%20Arrow_zpsbwxgi0j8.jpg





Because of this arrangement, the hammer MUST rock back further in single action mode than when it is released in double action mode. I have never heard velocity of the hammer discussed, but I can tell you when the hammer is cocked single action, because it has been forced back farther, the hammer spring has been compressed more than it gets compressed in double action shooting. Because of this, the hammer falls with more force when cocked single action than when the trigger is pulled double action.

Many years ago the engineers at S&W realized that the amount the hammer spring was compressed when the trigger was pulled double action was all that was needed to fire a primer. The extra distance the hammer moved back when cocked single action compressed the spring more than was necessary to fire a primer.

So the Short Throw hammer was developed. I believe sometime shortly after World War Two. There were a couple of different designs of Short Throw hammers, but eventually the modern design was settled on. At the top of this photo is the Model 14-3 with the hammer cocked. At the bottom is an older 38 Military and Police Target Model, also with its hammer cocked. Notice the greater angle of the hammer on the older revolver. The Short Throw hammer cocks the hammer just barely past the point where a double action pull on the trigger would release it. Just barely. Even so, with the Short Throw hammer the hammer spring has been compressed slightly more than when the gun is fired double action.

Model%2014-3%20and%20MampP%20Target%20Model%20Hammers_zps2nhyvhku.jpg
 
This got me pondering: Is the terminal velocity of the hammer faster when firing single action? Is the rearward distance of the hammer also greater when firing single action?
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Yes and yes.

This is why it is CRITICAL to test a modified revolver in both single- AND double-action before relying it for self-defense. If one puts in a spring kit and only tests the gun in single-action they haven't really verified that it will work 100% in double-action where the hammer travel is reduced and therefore the hammer doesn't strike with the same amount of force.
 
I'd be interested in the revolver used for that experiment. I would think that an older style revolver with the firing pin on the hammer would do better than a modern flat-faced hammer used for transfer bar firing pins.

Water is somewhere around 1,000 times more dense than air so that flat face would theoretically be slowed down more than the more aerodynamic (fluiddynamic?) hammer with a pointed firing pin on it.
 
Water resistance was slowing the bullet. Nothing to do with the hammer. The hammer is powered by a spring. And the hammer doesn't travel far enough for the water to do anything but make it wet.
Shoot out scenes from action movies have nothing to do with reality either. They're always about how much 'action' there is, period.
 
T. O'Heir said:
Water resistance was slowing the bullet. Nothing to do with the hammer. The hammer is powered by a spring. And the hammer doesn't travel far enough for the water to do anything but make it wet.
Shoot out scenes from action movies have nothing to do with reality either. They're always about how much 'action' there is, period.
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What are you talking about?

The thread is about the light primer strikes when shooting double action vs single action. Whether the hammer travels an inch or a foot underwater the same resistance is there.
 
T. O'Heir said:
And the hammer doesn't travel far enough for the water to do anything but make it wet.
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I seriously doubt that. I'm betting water adds quite a lot of resistance - and once it's slowed down through much of it's arc, it still has to displace the water between it and the primer. And without an easy exit for this water, I suspect the energy lost to this displacement alone would be enough to cause reliably issues.

And yes, to the OP, as others have noted - the SA hammer starts it's arc further back, and as a result, is traveling faster at the end of it's arc, and more likely to light off a primer even if the DA hammer doesn't.
 
Firing a gun submerged is a risky proposition. Failure to ignite may not be too bad a feature.

-TL

Sent from my SM-G930T using Tapatalk
 
Thanks, Driftwood!

The willingness of others to disassemble their guns to answer questions keeps me asking questions on The Firing Line.
 
Firing a gun submerged is a risky proposition
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Yes, water does constitute a blockage and may cause over pressure in anything but a Hi-Point. I wonder if it would be safer in a revolver though. Certainly not something to do just for fun.

Also, if the water is also outside the gun pressure is acting on the externals also, so it may re-inforce the gun, but probably not to a significant amount.
 
OK, it will cause over pressure, that over pressure MAY cause a catastrophic failure.
On the plus side, if the gun does blow it will be far less dangerous as the water will slow any debris quickly. I think it would be hard on ones ears though.
 
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