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View Full Version : CZ 75 weird firing pin strike...help diagnose


bsumoba
11-19-2012, 6:14 PM
So I installed a CGW extended firing pin, race hammer, and springs (11.5lb mainspring, reduced power firing pin spring, reduced firing pin block spring) in my CZ75 SP-01 and P-01 (not sure which one as i was shooting both and collected most of my brass at the end) and upon reviewing the firing pin strikes to see how the primer strikes were doing (depth, shape, etc) I noticed this kind of strike. This was on a number of primers. I cleaned the gun and inspected the firing pin when i got home and does not appear to be misshapen.

Any ideas?

Some thing to note: All ammo ignited and shot well. used LAX reloads, and Speer Gold Dots. 115 gr, 124 gr, and 147 gr all used.


http://i1253.photobucket.com/albums/hh586/Bryan_Sumoba/2012-11-19_18-30-21_187.jpg

zfields
11-19-2012, 6:57 PM
Non issue.

dangerranger
11-19-2012, 7:05 PM
I would look to see if the firing pin was retracting! load a spent case and fire on it then open the action and see if the firing pin is sticking out. Id try it a couple of times to be sure. If it is hanging up be ready for a slam fire! Good Luck DR

MA2
11-19-2012, 7:09 PM
Looks normal to me.

The teardrop is normal for a tilting barrel.
The spent casing is moving with the barrel, while the firing pin is still extended.

Carsgunsandchics
11-19-2012, 7:12 PM
Looks normal to me.

The teardrop is normal for a tilting barrel.
The spent casing is moving with the barrel, while the firing pin is still extended.

Yuppers, it's called firing pin swipe. It's normal.

Rust
11-19-2012, 7:47 PM
It is not normal. Your firing pin is supposed to have retracted before the barrel unlocks from battery. It's not inherently bad, but it's not normal. Likely cause is a combination of light action springs (reduced power main) allowing the action to unlock before the reduced power firing pin spring is able to move the extended pin out of the way. Generally if you're going to run reduced power main or recoil springs you need to run light loads, which Speer Gold Dots are not. It's not going to cause problems right away, but if it happens on a lot of shots fired, and you shoot a lot it will eventually start to wear the nose of the pin away at an angle, and or potentially push a bur down which could cause the firing pin to stick in its tunnel.
I've recently done similar spring changes in my 75 and have not shot it yet so I'm curious to see if I get the same problem.

JeremyS
11-19-2012, 7:47 PM
Firing pin swipe is normal. Many factory (unmodified) guns do it. You have an extended firing pin now with a spring that doesn't return it back into the channel as quickly as the stronger factory spring. Certainly makes this more likely.

BTW, I'm impressed at how solid and deep that primer strike is with an 11.5 lb spring! I would think that you'd need really soft primers (Federal, etc) to actually get reliable ignition with a spring that soft, but it seems that along with your other mods are working great. That's a totally perfect hit there.



It is not normal. ...it will eventually start to wear the nose of the pin away at an angle.

I've had more factory new guns that did this than didn't. It's very much normal. Ideal? Maybe not. Normal? Yes. Problem? Not likely unless it's pretty bad and the swipe in the photo is normal/minor. It will no more wear your firing pin away than striking primers flattens your firing pin. Primers are soft and the firing pin in question is hardened tool steel. I just don't think it's truly the issue you think it is. If you have to replace a firing pin after 20,000 rounds or something... I mean, swipe or no swipe you'll get there eventually...

bsumoba
11-19-2012, 8:59 PM
BTW, I'm impressed at how solid and deep that primer strike is with an 11.5 lb spring! I would think that you'd need really soft primers (Federal, etc) to actually get reliable ignition with a spring that soft, but it seems that along with your other mods are working great. That's a totally perfect hit there.


I emailed CGW and he mentioned this is normal with the setup I have. Because the FP is S-7 tool steel, I'm good to go and should not see any wear.

The Speer's actually had very nice strikes. The LAX reloads I have from the Crossroads of the West shows (115 gr, not sure what type of primer) actually showed slightly less of an indentation. It was still solid and had no issues (fired off about 40 rounds in each gun) with ignition or any other type of firing issue.

schmeky
11-20-2012, 6:22 PM
It is not normal

Yes sir, it can be. Regular firing pins are made from a fairly low grade of steel, then heat treated to make them viable. To make them survive, they are fitted with heavy firing pin springs to make them retract quickly so they all they have to do is hit the primer.

S-7 tool steel is tuff as hell, ask any machinist. Then when you heat treat it, it becomes super-tuff, yet retains it's flexibility; the striking end will never wear.

So now you can reliably run lower power FP springs with lower power hammer springs and have excellent ignition. This results in very low DA pull weights, in the 6-7.5 pound range. You should try a DA like this. It's most impressive.

BTW, that is very deep primer indention for an 11.5# hammer spring.