Author Topic: Primer deformation or. . .  (Read 286 times)

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Offline Earl Keese

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Primer deformation or. . .
« on: January 19, 2018, 09:59:18 PM »
Noticed this at the range today. I was shooting Acme 124rn w/ 4.2gr of HP-38. The Blazer case is from my P10C, the FC was fired from my Scorpion Carbine. Looking at the primers, the one from the Scorpion is raised in the center while the other is not. Is this just from the profile of the Scorpion firing pin or a pressure sign? I haven't had an opportunity to look at the firing pin yet.

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Offline Scarlett Pistol

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Re: Primer deformation or. . .
« Reply #1 on: January 19, 2018, 10:29:23 PM »
Following to hear what the thoughts are.
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Offline IDescribe

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Re: Primer deformation or. . .
« Reply #2 on: January 19, 2018, 11:38:15 PM »
Different firing pins/strikers leave different marks.  The fit of the striker/pin to the hole in the breech face through which it passes can affect the mark.

The edges of the primer are still nice and rounded.  I don't see anything to worry about.  BUT I will say that if you take pics of primers to show an audience, take it from 45 degrees, or even a little lower.  When you're straight over the top like that, it makes it 2-dimensional, and it's difficult to see what's happening.

Offline 1SOW

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Re: Primer deformation or. . .
« Reply #3 on: January 20, 2018, 12:24:36 AM »
I agree with ID.
There's no primer cup 'flow' or significant deformation.  The two weapons will have two different firing pin strikes and pressures generated for sure.  The FC & Blazer are fairly soft cases that may look different than harder cases like  Win NATO, PPU,WIN or R&P.  Some of these may also look a little different than the others depending on how they seal with your load.

A chrono check might show "the rest of the story".
 

Offline Wobbly

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Re: Primer deformation or. . .
« Reply #4 on: January 20, 2018, 06:46:14 AM »
I agree with ID.

A chrono check might show "the rest of the story".
 

I agree with ID and 1SOW.

The corners of the primers are too rounded to worry about any pressure issues. Primers are one of those items everybody looks at, but which are terrible indicators.
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Immature reloaders ask: What's wrong with this gun?
Mature reloaders ask: What did I do wrong ?

Offline painter

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Re: Primer deformation or. . .
« Reply #5 on: January 20, 2018, 06:53:13 AM »
I agree with Wobbly that primers are not a very accurate indicator of pressure.
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Offline Wobbly

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Re: Primer deformation or. . .
« Reply #6 on: January 20, 2018, 07:00:09 AM »
When your primers look like the one on the far right....




...then you can start to worry.  O0
In God we trust; On 'starting load' we rely.

Immature reloaders ask: What's wrong with this gun?
Mature reloaders ask: What did I do wrong ?

Offline Earl Keese

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Re: Primer deformation or. . .
« Reply #7 on: January 20, 2018, 07:20:37 AM »
  I suspected it was the FP but you guys know more than I do and I wanted to confirm. Sorry about the pics, I tried at can angle but couldn't get a good shot with my phone.
  I'm going to shoot them over the Chrono next week but there's a PCC match tomorrow and I wanted to try my hand if possible. I really appreciate being able to come here and get quality information. Thank you.
« Last Edit: January 20, 2018, 07:28:39 AM by Earl Keese »

Online M1A4ME

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Re: Primer deformation or. . .
« Reply #8 on: January 20, 2018, 07:23:47 AM »
If there's enough difference between the diameter of the firing pin and the diameter of the firing pin hole in the slide you can get deformation of the primer cup metal - flowing back into the firing pin hole around the firing pin itself.

Seen that quite a few times over the years.  That was the problem with the early S&W 686's back in 82 or 83.  In the revolvers it would actually lock up the cylinders (aggravating at the range, deadly on the street).  The fix was to sent them back for a firing pin nose bushing replacement (fully half of our went back).

In a semi auto it's not an issue because the brass doesn't have to move against anything, it just gets pulled to the rear and smacked off the slide by the ejector.

As everyone said, keep on shooting and enjoying it. 
Better to have it and not need it, than to need it and not have it.  So, if you see me walking the dogs with my SIG 556R, its okay.