Monday, May 25, 2015

Hammer Fired vs. Striker Fired

In the world of modern firearms which use centerfire cartridges, there are two major types of mechanisms used to trigger the cartridge primer. One uses a hammer and another uses a striker. Therefore, mechanisms that use a hammer are called hammer-fired and the ones that use a striker are called striker fired. As you can guess, each mechanism has its own group of supporters. In today's post, we will study what this all means.

In a hammer fired mechanism, the hammer is a heavy piece that is allowed to rotate about a pivot point. When the hammer is cocked, it compresses a spring. When the trigger is released, the spring pushes the hammer and forces it to rotate forward. The end of the hammer strikes the back end of a firing pin, which is a thin steel pin with a hardened tip. The front end of the firing pin strikes the primer of the cartridge, thereby detonating it. The image below shows how this works.


In some revolvers, the firing pin is attached to the hammer directly.

Firing pin attached to the hammer of a Smith & Wesson Model 13 revolver.
Image licensed under Creative Commons Attribution-Share Alike 3.0 Unported license.

In either case, the key part of the mechanism is a rotating hammer mechanism. Here's another animation showing the same concept.

The main thing that we conclude after looking at all the images above is that a hammer-fired weapon is a rotating type mechanism.

In contrast to this, striker fired systems operate in linear fashion. The striker is a part that is a bit heavier than a firing pin and it is directly connected to a spring. When the firearm is cocked, the striker is moved against a linear spring and held in position. When the trigger is released, the spring forces the striker forward with enough energy to detonate the primer upon impact. The animated image below shows how this works.


The striker is the long part in the back of the gun that looks like this:


It should be noted that the animation example for a striker fired weapon shows the firing mechanism of a Glock pistol. When a Glock is cocked, the striker is moved back and held under partial spring tension by the trigger mechanism and safety devices. As the trigger is pulled, the striker is initially pulled back till the spring reaches full tension and then the striker is released. In other pistol models, such as Springfield XD or Smith & Wesson M&P models, the striker is already held at full spring tension when it is cocked. Pulling the trigger in such firearms merely releases the striker and allows it to fly forward

From the above images, we see that hammer fired mechanisms use a rotational force to detonate the primer, whereas striker fired mechanisms use a linear force to do it.

Striker fired mechanisms tend to have fewer parts than hammer fired mechanisms and are therefore simpler. However, they take up a bit more room. This is why firearms that don't have bolts, such as revolvers, use a hammer-fired action. Revolver and many types of single-shot action firearms generally don't have the room to accommodate a striker mechanism.

Strikers are commonly found in many modern semi-automatic pistols, bolt action weapons and shotguns. In fact, the first striker fired weapon invented was a shotgun invented by Daniel LeFever in 1878. Another example of a striker fired weapon is the Czech vz.58, which we studied earlier (contrast this with the similar looking AKM rifle, which uses a hammer fired mechanism). Striker fired pistols started becoming popular in the 1980s, when Glock started using them on their pistols. However, it must be noted that Glock weren't the first to use it on pistols either: John Browing used it in the .25 caliber Model N pistol and the H&K P7 is striker fired as well. Nevertheless, once Glock started becoming popular, other manufacturers also started using the same idea on a larger scale and now you have several pistol models, such as Smith & Wesson M&P, Springfield XD, Ruger SR9 etc. However, there are some famous pistol models that use a hammer fired mechanism instead. Examples include the Colt M1911, Browning Hi-Power, Beretta M9 etc.

A striker fired mechanism doesn't have an exposed hammer, so it cannot get caught in clothing, shrubs etc. The fact that it has fewer parts means easier maintenance as well. Another positive is that it has a consistent trigger pull for every shot (in contrast to double action/single action hammer fired mechanisms, where the trigger pull force is different depending on whether the firearm is working in single action mode or double action mode). Striker fired mechanisms generally have a consistent trigger reset as well.

On the other hand, if there is a malfunction on a striker fired weapon because the primer didn't detonate, the only option is to eject the cartridge and try the next one. With a hammer fired firearm, it may be possible to try again on the same cartridge (on models that provide this second-strike capability). Hammer fired guns also generally impact primers harder than strikers do, thereby giving a better chance to detonate them. It is for these reasons that many military forces prefer hammer fired weapons. For example, the US military's choices of weapons: Colt M1911 pistol, Beretta M9 pistol, M1 Garand, M14 rifle, M16 rifle, M4 carbine etc. are all hammer-fired.

The video below shows some of the advantages and disadvantages of each system:


As you can see, each mechanism has its own group of fans that argue about which is better. Happy viewing.

6 comments:

  1. 1: there are some hammer-fired firearms with an internal hammer that you can't see (and they can't get caught on clothing either; you seem to infer that all hammer-fired guns are prone to this towards the end of the article).
    2: the Glock animation is wrong; the entire slide/barrel assembly ought to move to the rear slightly as the bullet it moving down the barrel. That's the whole point, that the fraction of an inch that they move to the rear together gives the bullet time to leave the bore before the slide unlocks, and continues to the rear. It's impossible for the assembly to remain stationary until the bullet is gone. The only way that works is if you have a very heavy bolt, which has enough inertia. That's a blowback weapon, and would make the entire unlocking mechanism pointless. But I'm guessing most people here know that already.
    3. Not all strikers look like that, they only look similar (to nit pick a bit)
    4. There's a simple term for guns that start with the hammer or striker cocked: single action. I was surprised you didn't even include the terms "double action" and "single action" for clarity. I remember when I was a small fry trying to glean all the info I could about firearms from various magazines. It's amazing how much you can piece together eventually, but it's much easier when people make it clear what they are talking about. I still remember how excited I was when I finally figured out what people meant by "stroker engine"; I'd heard the term for years, but it wasn't until someone finally just came out and said it plainly that I figured it out (they didn't have new-fangled things like Wikipedia back then).
    5. A consistent trigger pull has nothing to do with whether a firearm is striker-fired or not. It's because they aren't a DA/SA. You can make either a hammered or strikered gun a single action or DAO, so I don't see why "striker = consistent trigger pull". I believe there is at least a variant of the Walther P99 that is striker fired and DA/SA as well. So, consistent trigger pull has nothing to do with being striker fired. There is no direct correlation.
    6. You say that you can't double-strike a misfire with a striker-fired gun. Again, that's only true if it's a SINGLE ACTION striker fired gun. A DA striker can double strike just as easily as a DA hammer-fired gun. The only difference is when you get into SA guns with exposed hammers; theoretically, you can manually recock the hammer, which you can't do with a striker-fired gun (but a lot of people would call that bad drill, and say that you're much better off practicing to immediately clear the misfire and chamber a new one. With a DA, it's a lot quicker to pull the trigger for a second try and THEN clear the gun, but I'd say that mucking about with trying to manually cock the hammer isn't worth the time). To say that "hammer fired guns can double strike and striker fired ones can't" is ignoring DA guns of doth types and the fact that an exposed hammer is really not worth a whole lot for double striking, except perhaps on the range.

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    1. Point #2 has an error. The reason for allowing the barrel and slide to move backwards together is to allow chamber pressure to drop to a level that will permit reliable extraction. THe bullet is long gone before any movement of the slide occurs.Calibers that developed lower pressure can get away with blow back operation.

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  2. Can you give me an example of a double action striker fire that can recock and release the striker again after a misfire by just depressing the trigger a second time (without racking the slide)?

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  3. I have two .22 revolvers, H&R 949s, one has an affixed pin to the hammer, one has a hammer that comes down and strikes a block which in turn strikes the pin. Can you tell me what the proper names are for this type of mechanism are and benefits of either? Do you have an entry wit hthis already? Thanks

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    1. Hi T. Bear, that mechanism on the second revolver is called a transfer bar and is a safety mechanism. Please see this post for more:
      http://firearmshistory.blogspot.com/2011/07/safety-mechanisms-drop-safety.html

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