Sunday, October 12, 2008

A .40 Caliber Mystery

Shown here from left to right are 9x19mm NATO, .40 S&W and .45 ACP cartridges.

This is a Blazer 40 S&W round which was fired in my Glock 22. The shot did not feel right so I unloaded and benched the pistol so I could track down my "brass." When I picked it up from the floor it looked strange but it took me a few seconds to figure out why. The first thing I noticed is the extraction groove does not exist anymore. T

Then I noticed that about 1/3 of the way along the case moving away from the primer was a small swelling. This is a 40 S&W round that was cycled through a .40 caliber Glock 22. It is not a 9mm round. It was a factory loaded aluminum cased Blazer round. The visible scratches on the case are most likely from carrying the case in my pocket.

Another shot of the case.

As you can see the extraction groove is gone. Fro this angle the sidewall of the case looks straight.

I inspected my Glock before reusing and I could find no problem with the pistol. The brass .40 caliber ammo I used afterwards all functioned normally. I will no longer use any aluminum cased ammunition in any of my Glocks.

If anyone has had any similar experiences, I would be interested to hear about it.

Updated on 10/22/08:

Some nice folks on the Gunboards Forum at:
were kind enough to suggest I contact Blazer with my pictures and questions. Here is their response:

The Old Salt: what you discovered was a rare incident of the case missing the "head-turn operation" during case making. In this instance it is not a matter of the extractor groove not "existing anymore", there never was an extractor groove on the case. Since the round was fired in a Glock and it has a rectangular firing pin, look to see if the bulge in the case matches with the feed-ramp in the barrel i.e. 6 o'clock or 12 o'clock when looking at the rectangular firing pin mark on the primer. That would be my guess as to the reason for the bulge. The disconnector on the Glock should keep it from firing when the slide is not "in-battery" a safety feature built into the gun.

Pressure and velocity from the round should equal that of the other rounds in the box as they would have all been loaded at the same time, no safety issue.

Since the cartridge headspaces on the case mouth it went into the chamber properly. What I find interesting is there must have been enough lip on the back of the case that the extractor was able to hook the case and extract it. Had that not happened, the next round would not have been able to feed as the case would have remained in the chamber blocking feeding of the next round.

Sorry for the problem, does that explain what and how it happened?

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