14 May 12
Follow-up on hammer-fired and striker-fired pistols, from a friend and design-engineer:
“Hammer vs striker design differences are a good showcase for the slippery topic of ‘engineering design-tradeoffs.’ Comparison of hammer-fired ignition systems and striker-fired ones graphically demonstrates at least one critical design difference:
Hammer-fired handguns have firing pins with relatively loose radial tolerances in the firing-pin channel, because all they have to do is move linearly along their axis and get guided through a relatively large firing-pin hole in the bolt-face. This loose radial-fit is beneficially forgiving of debris accumulation (at least up to a point). Sear-engagement and trigger-pull quality issues are focused on hammer and sear designs, and do not involve the firing-pin itself. Downsides of hammer-ignition are increased numbers of accessorial moving parts, additional space that they consume within the handgun envelope, increased parts-breakage, and increased ignition delay.
Conversely, striker-fired systems have none of the above-defined disadvantages, because there is direct engagement of the striker with the sear mechanism, and thus fewer parts, all taking up less space.
However, strikers necessarily have precious little radial slop in their channels. If strikers did have generous radial clearance, they could cant within the striker channel, generating unreliable sear engagement and erratic trigger-pull. Unhappily, this tight radial clearance will not forgive much accumulated debris, nor congealed lubricant, in the striker-channel, and, as you noted, such massed contamination can yield reduced striker transfer-energy to the primer. The main symptom is, of course, shallow primer-dents and occasional failure of a round to discharge normally.
Manufacturers can counterbalance lack of lubricant by using striker-channel liners with intrinsic high lubricity, as Glock does, or coating firing pins with a high-lubricity, permanent surface treatment such as NP3. Slots or flutes can also be formed in the striker outer circumference and/or striker channel, and will have similar effect.”
From another trainer:
“Hammer-guns need clean and dry firing-pin channels, too! A few years ago, I drew my S&W 6906 (now largely superceded by S&W’s M&P Series) during a practice-session in January, only to hear a ‘click,’ instead of the expected report. Later, in my warm hotel room, I disassembled the pistol and found moisture in the firing pin-channel. It didn’t require much encouragement for it to freeze solid, rendering the pistol sterile!”
And another trainer:
“When cleaning any striker-fired pistol, continuously keep the muzzle-end down, so solvent and lubricant does not, even inadvertently, drain into the firing-pin channel. Notwithstanding, no matter how assiduously one maintains his pistol at the user-level, it still needs to get in front of an armorer once per year. Fail at your peril!”
The “striker” on a “striker-fired” pistol is little more than a spring-loaded firing pin. With such pistols, no moving hammer is visible to the shooter as the trigger is being pressed to the rear. By contrast, moving hammers are visible on most current trigger-cocking, hammer-fired pistols. Some instructors think a moving hammer is distracting to shooters. Others say it is a non-issue. I fall in the latter group!
However, for better or worse, striker-fired pistols currently represent the “trend,” and marketing momentum in that direction will not likely reverse any time soon.
For one, I consider both systems eminently satisfactory and usable for serious applications, but neither is perfect, and, as with all emergency equipment, there is no viable substitute for competent maintenance, adequate redundancy… and eternal vigilance!
“Things one feels absolutely certain about are never true. That is the frailty of faith, and the lesson of romance!”