Fooey: CZ-70

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lklawson
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Fooey: CZ-70

Post by lklawson »

Some of you may remember that I lightened the hammer spring of my CZ-70 because it was beastly heavy, two-finger strong, in DA.

I referenced it here: viewtopic.php?f=10&t=4594

And my encouraging results with Fiocci here: viewtopic.php?f=10&t=4677&p=44893

Additionally, I loaned it to a friend who wanted to do some experimenting with his own hand-loaded .32ACP. Except for that one fail to fire with Fiocci, it was all good.

Until yesterday, that is.

I took my CZ-70 to give it a little range love. I have a half-dozen boxes (300 rounds) of PPU ammo so I too a box of that. Out of 25 rounds attempted fire, about half failed to ignite! One of them fired after multiple strikes. The others just laughed at me no matter how many times I dropped the hammer on them. I ejected the rounds and examined the primer. Yup. There was a primer strike showing but it was clearly light.

PPU ammo uses harder primers than the other stuff I've run since I lighted the hammer spring.

Conclusion: If I want to be able to use and trust PPU ammo, or any ammo, really, I'm going to have to shore up the strength of the hammer spring.

It's a shame too, the current pull is really nice. It's a bit lighter than my Ruger Security Six and definitely lighter than most of my autos in DA.

A friend tells me that I can add washers or other spacers on the Hammer Strut below the spring to give it some extra compression. That might do the trick. If not, I still have the original spring I can put back in but I would rather order a spring from Wolff Gunsprings (again) and just clip off fewer coils.

I'm pretty sure I can get it to fire reliably and still have a lighter trigger weight than stock. Just a matter of finding the sweet spot.

Peace favor your sword,
Kirk
The Cheapskate's Guide to Gun Cleaning and Maintenance - "You shouldn't have to spend thousands of dollars on expensive gun cleaning an maintenance products. Find out how to save money with inexpensive alternatives that work just as well."
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lklawson
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Re: Fooey: CZ-70

Post by lklawson »

I stacked three zinc plated flat steel washers under the hammer spring, for a total of ~1/8" and took it shooting again. This configuration gave about a 15-20% heavier trigger, like a very heavy revolver, and reliably ignited the PPU (Igman) primers 95-98% of the time.

The firearm was reliable with S&B and my buddy's hand-loads so I am quite satisfied with the result and the conclusion that the PPU just has very hard primers.

Peace favor your sword,
Kirk
The Cheapskate's Guide to Gun Cleaning and Maintenance - "You shouldn't have to spend thousands of dollars on expensive gun cleaning an maintenance products. Find out how to save money with inexpensive alternatives that work just as well."
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