The original M&P strikers were machined, meaning not MIM, and they sometimes exhibited a broken head (at the machined groove) when dry-fire was involved.
The bottom M&P striker is the original design, and the yellow arrow shows the machined groove where the head might sometimes break.
Striker redesign resulted in a heavier MIM design, because they determined that MIM would allow them to make a stronger striker.
The rounded tips of firing pins, whether forged/cast machined or MIM, may be subject to breakage, pitting or corrosion. That's why armorers have been told to periodically inspect the firing pin tips for damage, chips or breakage for years, regardless of the manufacturing method.
Glock had another problem influence surface related to their striker-type firing pins, and it involved the use of some "green" ammunition used by some agencies. If the chisel-shaped firing pin tip punctured a primer, the corrosive gasses could erode the tip. We (armorers) started being told in recert classes to make sure we carefully inspected the firing pin tips periodically, and especially if green/non-tox ammo was being used.
FWIW, it appears that the traditional rounded firing pin tips can be less susceptible to damage and less likely to perforate primers than the chisel-pointed tips. Coincidentally, the FBI's new Project M (Gen5) series Glocks had a firing pin redesign.
Now, also consider that traditional pistol firing pins were long and tapered, and the tips protruded through the breech face holes as the tapered shape allowed. No heavy impact against the back of the slide's breech face. Just a tapered pin slipping through a hole.
Many modern striker-fired firing pins have large heads that impact against the rear of the breech face, and only the chisel or rounded pin tips protrude through the hole. Dry-fire means the heavy, flat head of the striker firing pin is hammering the rear of the breech face during dry-fire, unless a suitably designed dummy round made for dry-fire is being used, to cushion the impact by allowing the tip to hit something and mitigate the impact of the striker's bead against the rear of the breech face.
MIM isn't the boogeyman, as long as the intended use of the part is suitable for MIM (it doesn't make a good "spring", for example), and the materials and manufacturing methods used are good quality.
Now, just as with previous complaints over the years of machined cast and forged parts sometimes suffering breakage and damage, not all parts are created the same.
Personal experience with an early production 2010 M&P 40c ...
After having used my 40c as one of my normal instructor training guns for a while, during an inspection I noticed the tip of the firing pin started to have a shiny spot being worn on the side. Odd, and nothing like I'd seen on my '08 production M&P 45 striker. I called and discussed it with one of the LE support guys at the factory, and the opinion was that it was probably a case of that particular striker's tip not perfectly aligning with the hole in that particular gun. He sent me a replacement striker and the issue wasn't repeated. (I later replaced both striker assemblies with the new designs, to try them out, just because I could, being a M&P armorer.)
In my own E-series Glock G27, I eventually had to replace the firing pin, trigger bar and the trigger mech housing in order to resolve a condition where the cruciform and firing pin engagement fell below minim spec. (As they'd started telling us in recert classes, sometimes replacing just 1 or 2 of those parts might not be sufficient to restore normal engagement, and they were right, as I tried different combinations of those 3 parts assemblies but didn't see a restoration of normal engagement until all 3 were replaced at the same time.
)
Periodic inspections of guns that see heavy use, or use in abusive and inclement conditions, is usually a good idea. Parts may wear, erode or break over time and use. That's probably why Glock has started referring to many of the parts and assemblies in their guns as "wearable parts", and S&W has started giving armorers a more structured recommendation for some of the M&P parts and assemblies, based upon a rounds-fired service interval.
Worrying about whether a striker-type firing pin might break or experience some other damage or wear doesn't keep me up at night.
Now, newly designed guns which are using newly designed parts, made using new manufacturing methods (for that manufacturer's model)? Well, I like to wait for a year or two before jumping on the bandwagon, and if it's a make/model for which I receive training as an armorer, I like to pay attention to recommendations offered by the company to armorers.
The bottom M&P striker is the original design, and the yellow arrow shows the machined groove where the head might sometimes break.
Striker redesign resulted in a heavier MIM design, because they determined that MIM would allow them to make a stronger striker.
The rounded tips of firing pins, whether forged/cast machined or MIM, may be subject to breakage, pitting or corrosion. That's why armorers have been told to periodically inspect the firing pin tips for damage, chips or breakage for years, regardless of the manufacturing method.
Glock had another problem influence surface related to their striker-type firing pins, and it involved the use of some "green" ammunition used by some agencies. If the chisel-shaped firing pin tip punctured a primer, the corrosive gasses could erode the tip. We (armorers) started being told in recert classes to make sure we carefully inspected the firing pin tips periodically, and especially if green/non-tox ammo was being used.
FWIW, it appears that the traditional rounded firing pin tips can be less susceptible to damage and less likely to perforate primers than the chisel-pointed tips. Coincidentally, the FBI's new Project M (Gen5) series Glocks had a firing pin redesign.
Now, also consider that traditional pistol firing pins were long and tapered, and the tips protruded through the breech face holes as the tapered shape allowed. No heavy impact against the back of the slide's breech face. Just a tapered pin slipping through a hole.
Many modern striker-fired firing pins have large heads that impact against the rear of the breech face, and only the chisel or rounded pin tips protrude through the hole. Dry-fire means the heavy, flat head of the striker firing pin is hammering the rear of the breech face during dry-fire, unless a suitably designed dummy round made for dry-fire is being used, to cushion the impact by allowing the tip to hit something and mitigate the impact of the striker's bead against the rear of the breech face.
MIM isn't the boogeyman, as long as the intended use of the part is suitable for MIM (it doesn't make a good "spring", for example), and the materials and manufacturing methods used are good quality.
Now, just as with previous complaints over the years of machined cast and forged parts sometimes suffering breakage and damage, not all parts are created the same.
Personal experience with an early production 2010 M&P 40c ...
After having used my 40c as one of my normal instructor training guns for a while, during an inspection I noticed the tip of the firing pin started to have a shiny spot being worn on the side. Odd, and nothing like I'd seen on my '08 production M&P 45 striker. I called and discussed it with one of the LE support guys at the factory, and the opinion was that it was probably a case of that particular striker's tip not perfectly aligning with the hole in that particular gun. He sent me a replacement striker and the issue wasn't repeated. (I later replaced both striker assemblies with the new designs, to try them out, just because I could, being a M&P armorer.)
In my own E-series Glock G27, I eventually had to replace the firing pin, trigger bar and the trigger mech housing in order to resolve a condition where the cruciform and firing pin engagement fell below minim spec. (As they'd started telling us in recert classes, sometimes replacing just 1 or 2 of those parts might not be sufficient to restore normal engagement, and they were right, as I tried different combinations of those 3 parts assemblies but didn't see a restoration of normal engagement until all 3 were replaced at the same time.
) Periodic inspections of guns that see heavy use, or use in abusive and inclement conditions, is usually a good idea. Parts may wear, erode or break over time and use. That's probably why Glock has started referring to many of the parts and assemblies in their guns as "wearable parts", and S&W has started giving armorers a more structured recommendation for some of the M&P parts and assemblies, based upon a rounds-fired service interval.
Worrying about whether a striker-type firing pin might break or experience some other damage or wear doesn't keep me up at night.
Now, newly designed guns which are using newly designed parts, made using new manufacturing methods (for that manufacturer's model)? Well, I like to wait for a year or two before jumping on the bandwagon, and if it's a make/model for which I receive training as an armorer, I like to pay attention to recommendations offered by the company to armorers.
