There’s no firing a gun without denting a primer (if you aren’t sure what that means, start with how a gun works). There are two primary ways to do that: hammer fired and striker fired. So, what’s the difference, and is one better than the other?
First and foremost, striker fired vs. hammer fired is totally distinct from double action vs. single action, DA/SA, SAO, DAO, etc. Both hammers and strikers offer all of these forms of operation.
Double action means that pulling the trigger performs two actions: (1) it cocks or finishes cocking the spring responsible for denting the primer, and (2) it then releases the hammer or the striker.
Single action means pulling the trigger does one action: it releases the hammer or the striker.
Hybrid designs (forms of DA/SA, or double-action/single-action) are available in both hammer-fired and striker-fired guns. Popularity of certain action types aside, there is nothing inherent about hammers or strikers that prohibits or really even favors any given action type.
So, then, what’s the difference?
Hammer fired guns
A spring-powered weight – typically steel – swings into the firing pin when released by the trigger.
That weight is called a hammer, and its impact on the back of the firing pin drives the pin into the cartridge’s primer. In some cases (revolvers — mostly old ones) the firing pin is integral to or attached to the hammer itself.
Hammers are more commonly seen on the outside of a handgun (an external hammer), but there are many designs with internal hammers. In almost all cases, the hammer and its spring – typically called the mainspring or hammer spring – are components of the frame of a pistol, while the firing pin is within the slide.
An external hammer provides manual control to the operator, whether that’s cocking or decocking the action, without the need to manipulate the slide.
Striker fired guns
In a striker fired gun, the hammer and mainspring have been eliminated from the frame. Instead, the mainspring has been moved up into the slide and acts on the firing pin directly. Except, now, the firing pin is called a striker. Rather than being hit by a hammer, it does the hitting itself.
When cocked against the tension of the striker spring, the striker contains all of the energy necessary to ignite a primer. Some striker fired guns are single action: the cycling of the slide fully cocks the striker and the trigger serves only to release it. Others are double action: the trigger pull fully cocks or finishes cocking the striker, then releases it. Some are DA/SA and may even have an external decocker (so you can keep a round chambered with the hammer down, for example). The Beretta M9 and the Sig Sauer P229 are among the best-known DA/SA handguns.
However, there is very rarely a mechanism other than racking the slide by which the operator can pre-cock an at-rest striker. The Heckler & Koch P7, seen above, is one exception.
Striker vs Hammer
A partial list of typical advantages of hammer fired handguns:
• Easy visual and tactile indication of cocked / not cocked status
• Manual manipulation to cock and decock
• More space for a larger, stronger mainspring and a thicker, heavier hammer (as opposed to an in-the-slide striker, which tends to have less mass)
• Additional options for remedial action, thanks to the ability to manually re-cock the hammer
• It’s often easier to manipulate the slide (with the hammer cocked) vs that of a typical striker fired pistol
• The average hammer fired pistol in single action has a better trigger than the average striker fired pistol
A partial list of typical advantages of a striker fired handgun:
• Fewer parts. This is true in most, but not all cases (see the Hudson H9 above). A Glock has 34 parts. A 1911 has 58. That’s total parts, and the difference in moving parts is even more pronounced.
• Lower cost
• Improved simplicity in function (“battery of arms” a.k.a. learning how to operate it), disassembly, and maintenance
• Lighter weight
• Smaller size
• A lower bore axis (how high the bore of the barrel is above the shooter’s hand)
In the hammer vs. striker debate, there are exceptions to every one of the generalities above, and there’s a gun of each type that can suit every safety, concealed carry, and shooting preference. Just about any combination is possible with either a hammer or a striker: cocked with safety on, partially cocked with a safety, partially cocked without a safety, double action only, DA/SA (with a decocker, with a safety, with neither, or with both), single action only with a safety, single action only with no safety, single action only with a trigger safety, etc.
If there’s one generality that holds up better than any other, it’s that striker fired pistols tend to be simpler with fewer parts and are therefore less expensive. They are often preferred by law enforcement.
At the end of the day, both hammer and striker serve the same function – to ignite a primer – and they can do it equally well. Rather than focusing on hammer vs striker, most of us would be better served by focusing on how well we shoot a given [reliable] firearm and how good of a fit it is for our hands and our carry and use preferences. Options and preferences for things like external safeties and methods of operation are much more important than whether it’s a hammer and firing pin or a striker that’s ultimately denting those primers.