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I made a trip to the range about a month ago (yes, I've been several times since), and after I got home, I found the two spent cases, pictured here, which had been ejected into my range bag on the floor behind me. For whatever reason, I didn't toss them right away (I'm not a reloader), and they were just sitting in a basket on the coffee table in our family room for a couple of weeks until I took this picture. I took the picture because I noticed the difference in the primer strikes and was curious about it.

The one on the left is from a Remington UMC "Mega Pack" yellow box of 250 which I bought at Academy a couple of days before that morning, and it was ejected from my H&K USP Compact. The one on the right was ejected almost certainly from a borrowed Glock (model number unknown to me at this time, but it was approximately the same size as my USPc) being fired by my wife in the lane immediately to my left. The person who provided her with that pistol also provided her with a sufficient amount of reloaded ammunition.

Like I said, I was struck by the difference in the two primer strikes and found it interesting. I don't know enough about this stuff to know what it means - if it means anything at all - but I was hoping some of you could enlighten me if the case on the right tells a tale about either the load, or the pistol that fired it. I will also be passing this information along to the pistol's owner in case it is something to be concerned about, but I was wondering what you all thought. I actually meant to post this a while ago, but I've been side tracked by life lately. Better late than never.

Thanks in advance for your input.

The primer on the left shows a normal "good" firing pin mark. It is centered, symmetrical, and the right depth as to indicate a good, strong hit.

The mark on the primer on the right shows some kind of a problem. The main strike mark is more or less round, slightly offset from center, and the right depth. But there is an unusual mark extending to the right. I'm not sure of the exact cause for this unusual mark. It might indicate excessive side play in the firing pin, or possibly that the firinng pin "bounced" and hit the primer more than once - the 2nd time possibly as the case began to be ejected. I can't tell for sure.

But I would say that the gun that that case came from should be checked out by a good gunsmith. I'll bet it has some kind of a problem.

frankie_the_yankee wrote: The mark on the primer on the right shows some kind of a problem.

It's a normal GLOCK indention. Their firing pins are rectangular in profile at the tip that contacts the primer. Scoop up a few more from other GLOCKs and you will see they all look like that.

No worries mate

I have a 1911 and a Glock and have noticed the same thing as you from my brass. I had always assumed that it was the ejector that caused the difference, but appreciate the insight into the difference in firing pins. A few pictures, not the best, but they may help clarify:

check out the end of the pin

My glock is the same way.... firing pin is rectangle and so is the hole in the slide for it.

if you want to really melt your noodle take a look at the origonal rem 597 .22lr and the newer 597 .22lr (the ones with the built in locks)

The old ones use the rectangle strikers and hit the far rim of the case.

The new ones use a round striker and hit about halfway between the center of the case and the rim.

The newer one will not burr up the chamber if you dry fire it

I would be interested in seeing one of the reloads fired in your H&K. It looks to me like there may be some overpressure indication (the raised area around the firing pin strike) on the Glock casing.

Any chance you have a few of the reloads left that you could try in the H&K?

bpet wrote:Any chance you have a few of the reloads left that you could try in the H&K?

Unfortunately, no. The individual who owns the Glock took the remaining unfired rounds home with him.

That's interesting about the shape of the Glock firing pin. Every centerfire firearm I've ever owned in caliber has had a pin that left a round indentation in the primer, just like the one shown in the picture. That covers 3 different bolt rifles chambered in .308 made by Remington, Ruger, and Savage, an AR chambered in 5.56mm, 4 different 1911s in .45 from Kimber, Sig, Taurus, and Ithaca, the H&K USPc in .40, a Colt Government in .380, a S&W Model 29 .44 magnum, a S&W Model 642 .38, and an old S&W Model 12 which I no longer own.

Is there some performance reason why Glock would shape their firing pin the way they did? The only reason I could think of is that perhaps they are easier to manufacture that way.

Interesting stuff...

The signature Glock firing pin strike is caused not by the shape of the firing pin but by the firing pin not being withdrawn during the unlocking stage of the gun's cycle. Many other striker fired guns exhibit a similar pattern just not to the extent of the Glock. My XD and my M&P both show a little of this, it is nothing to worry about.

The Annoyed Man wrote:Is there some performance reason why Glock would shape their firing pin the way they did? The only reason I could think of is that perhaps they are easier to manufacture that way.

This may explain Glock's design. http://guns4u.info/?cat=54 The firing pin is rectangular in cross-section with a chisel-shaped tip. Although primers are left with an instantly identifiable indentation, the striker’s unorthodox configuration produces less drag on the primer (eliminating the possibility of firing pin breakage) and concentrates its momentum onto a smaller area to insure positive ignition. Although I can't vouch for the accuracy of this explanation, it sounds plausible to me. I have heard that Glocks are very reliable.

WildBill wrote:

The Annoyed Man wrote:Is there some performance reason why Glock would shape their firing pin the way they did? The only reason I could think of is that perhaps they are easier to manufacture that way.

This may explain Glock's design. http://guns4u.info/?cat=54 The firing pin is rectangular in cross-section with a chisel-shaped tip. Although primers are left with an instantly identifiable indentation, the striker’s unorthodox configuration produces less drag on the primer (eliminating the possibility of firing pin breakage) and concentrates its momentum onto a smaller area to insure positive ignition. Although I can't vouch for the accuracy of this explanation, it sounds plausible to me. I have heard that Glocks are very reliable.

Thanks for the link, Bill. The following quote appears in your link:

Examination of the empty cases revealed an elongate smear on the primers which extended beyond the peculiar indentation usually associated with the Glock firing pin. My friend and highly regarded handgun authority Wiley Clapp has concluded that this is evidence of the rapid pressure peaks and resulting high slide velocities associated with almost all pistols chambered for the .40 S&W cartridge. Apparently the breech starts to open before the firing pin has retracted, producing the wipe mark noted.

If Wiley Clapp's assertion is true about this phenomenon being inherent to the .40 S&W cartridge is true, then other brands of pistols chambered in that caliber produce the same effect on their primers regardless of firing pin shape, and this should be a fairly regularly observable phenomenon. MY USP doesn't do that, and this is the first time I've ever seen it. Has anybody else seen this happening in say Sigs or S&Ws for instance?

Has anybody else seen this happening in say Sigs or S&Ws for instance?

I have never seen it in my 40S&W Sig. I have read that early model Sigmas had a rectangular firing pin, but Glock sued and S&W changed to the round pin.

WildBill wrote:

Has anybody else seen this happening in say Sigs or S&Ws for instance?

I have never seen it in my 40S&W Sig. I have read that early model Sigmas had a rectangular firing pin, but Glock sued and S&W changed to the round pin.

I wonder then if a round pin precludes the "wipe mark" from happening... ...in which case Clapp is right about Glocks, but wrong about almost every other pistol in .40 S&W.

The Annoyed Man wrote:I wonder then if a round pin precludes the "wipe mark" from happening... ...in which case Clapp is right about Glocks, but wrong about almost every other pistol in .40 S&W.

I also wonder. I would think a round pin, rather than a chiseled pin would not create a "wipe mark." But that's just my guess.