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Light primer strikes questions


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Old 01-11-2017, 01:39 AM   #1
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Default Light primer strikes questions

Using a G34. I have about 5-6K rounds thru it. Today at the range, using the same handloads as usual with CCI primers, I had 4 out of 80 rounds fail to fire. up until now I may have had 1 or 2 out of 3500 or so. I tried these 4 again in the G34 and they again did not fire. Tried them in the CZ P-07 i had also brought today and all 4 fired no problem.

The attached photo is a typical strike from the G34 today. I have never really paid much attention to what the strike looks like after firing. Does the photo look like a typical Glock strike? I have not modified the striker or spring in any way.

Also, can someone explain to me why the rectangular raised area on the primer around the striker hit appears? Is that typical for a Glock? It matches the cutout on the breech face that the striker comes through, but I don't know why it appears. Is the case expanding back that much that it presses the primer back and makes that impression?


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Old 01-11-2017, 03:25 AM   #2
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Yes; this pattern is quite typical for a Glock and is how I can tell when a Glock was used with the ammunition. The square pattern is caused by the primer material being forced into the area where the striker resides as the cartridge is fired.

Silly question, but after 5-6K rounds, has it been cleaned? Not a sarcastic comment, but I hear that some shoot their pistols and never clean them and have no issues. I clean mine after every trip to the range and there is always carbon built up in the nooks and crannies. It could be that you have some crud built up at the front part of the striker.

Here you can see a standard round firing pin pattern on the left and a Glock fired cartridge on the right:

Light primer strikes questions - Glock Forum

Hope this helps!



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Old 01-11-2017, 04:38 AM   #3
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By the full indentation of the striker head on the primer; I'd say you got a good strike. You may have a batch of poor quality control primers. Try some new cheap ammo by Winchester or Federal to see if it's your striker spring, or build up.

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Old 01-11-2017, 01:41 PM   #4
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That is a standard Glock strike. It's not the CCI primers, they are probably the best available, next to Federals, which are the most expensive. Plus the fact the rounds went bang in your CZ, dead primers don't go bang. Light primer strikes in Glocks are normally caused by one, or more, of 3 issues. Weak firing pin spring, but if your gun only has 5-6K on it, no, but check it for length, new springs are 2.540". Dirty firing pin bore and spot face. It has to be clean and dry, especially the spot face, where brass flakes can build up. High primers, which is normally caused by difference is seating pressure. You didn't say what your press is, if you are using range brass, or your load, bullet weight and type, OAL, powder and charge weight. One thing that should not be there is the mark on the brass (2 arrows on the left), that brass was not originally fired in a Glock. Another thing is the lower part of the firing pin mark, that is not normal either (right arrow).



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Old 01-11-2017, 02:11 PM   #5
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Were the light strikes centered or off-center on the case?

Off center would indicate the gun being out of battery. 5k is about the expected life of the Recoil Spring Assembly. If that spring hasnt been changed, change it. When it starts to become weak the gun can fail to return to full battery resulting in light off-centerd strike.
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Old 01-11-2017, 03:08 PM   #6
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Quote:
Originally Posted by Supercharged1 View Post

Also, can someone explain to me why the rectangular raised area on the primer around the striker hit appears? Is that typical for a Glock? It matches the cutout on the breech face that the striker comes through, but I don't know why it appears. Is the case expanding back that much that it presses the primer back and makes that impression?
As soon as the primer paste 'explodes', the expanding gases of the primer 'slam' the primer cup against the breech face and the cartridge case forward slightly... how far depends on the headspace clearance. (Yes, initially, the primer cup is actually pushed out of the case primer pocket just a bit.)

Then, when the powder ignites, the expanding gases of the powder 'slam' the case rearward against the breech face, reseating the primer cup 'flush' with the base of the case.

These two violent 'high pressure' events imprint the primer cup and the base of the case with the firing pin point and other breech face 'imperfections'.

Hope this helps.

Best regards,

Bob

Last edited by rbbeers; 01-11-2017 at 04:35 PM. Reason: 'Cleaned up' post.
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Old 01-11-2017, 04:51 PM   #7
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Don't think its a recoil spring. I've run 15lb and 13lb springs in competition guns and never had an issue with CCI primers or off center strikes. A Glock can't fire unless it's closed anyway. And besides the OPs pic shows a centered strike. Plus I've gone for over 20K on my G17s without changing springs. My experience says its a reloading issue. Will know more when the OP posts his method of loading.
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Old 01-11-2017, 06:15 PM   #8
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Quote:
Originally Posted by SixG17s View Post

A Glock can't fire unless it's closed anyway.
Actually, it can.

My G17.4 will release the firing pin 0.090" out of battery and produce a high primer strike as indicated by the red arrow here.

The 'old' primer strike that I flattened, so I could use the primer cup for the test, is indicated by the green arrow.

For what it's worth...

Best regards,

Bob
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Old 01-11-2017, 06:28 PM   #9
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rb, that still looks like a high primer. It has no rectangle imprint. I've never been able to get a Glock to click (on a dummy load) until it's almost closed, more like .020"
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Old 01-11-2017, 06:59 PM   #10
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Quote:
Originally Posted by SixG17s View Post

rb, that still looks like a high primer. It has no rectangle imprint. I've never been able to get a Glock to click (on a dummy load) until it's almost closed, more like .020"
Six,

About an hour ago, I performed an experiment with an empty case and used primer cup to determine just how far out of battery my G17.4 would release the firing pin and how high the firing pin would strike the primer cup.

The firing pin released with the slide about 0.090" out of battery and struck the primer cup as shown in the picture above (post #8).

Your experience notwithstanding, my results are what they are.

Best regards,

Bob

ETA: For what it's worth, experiments with my G26.3 and G27.3 yielded similar results.



Last edited by rbbeers; 01-11-2017 at 08:08 PM. Reason: 'Cleaned up' post. Added ETA.
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