CZ-70's infamous DA trigger

[lklawson]

To recap:

I sanded smooth and then polished the Firing Pin Lock (part #9) and the channel in the slide in which it fits.

I replaced the Firing Pin Lock Spring (#8) with a lighter strength spring I salvaged & cut to size from a butane lighter.

I polished the Hammer Strut (#24) where it meets the Hammer Spring (#25).

I replaced the Hammer Spring with a new-old-stock spring and trimmed ~3/8" off of it.

I tested with the old Hammer Spring with 100% function.  After the shortened Hammer Spring, I ran 26 rounds of Fiocci.  25 rounds went down the pipe perfectly and the 26th round required a second strike.  This may or may not have been a fluke or may have been a light strike.  However, I'm out of .32ACP ammo for the moment.  I have a few hundred rounds of Prvi on the way that I can test with next.

The shortened Hammer Spring truly does make the DA trigger on this firearm useful so I'm really pulling for the double-strike to be a fluke.

On the informational side, with the shortened Hammer Spring, the recoil was slightly more snappy.  I probably wouldn't have noticed it if I hadn't been warned that it might happen.  So, it isn't a whole lot but it is noticeable if you're paying attention.  A friend warned me that it is his estimation that one of the reasons some Commie guns have such stiff Hammer Springs is to absorb a bit more of the recoil.



Peace favor your sword,
Kirk

[lklawson]

Well piffle!

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 took 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.  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.

Peace favor your sword,
Kirk

[Powerpuff boy]

That's too bad.  I am resigned to the fact that I would have to deal with the heavy DA.  And I have started using a squeeze ball to strengthen my finger/grip.   Who said shooting was not healthy?   

[lklawson]

That's too bad.  I am resigned to the fact that I would have to deal with the heavy DA.  And I have started using a squeeze ball to strengthen my finger/grip.   Who said shooting was not healthy?   

Well, I am pretty sure that I can still reduce the trigger weight.  I just reduced it too much the first time 'round.  :)

Peace favor your sword,
Kirk

[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 100% reliable with S&B so I am quite satisfied with the result and the conclusion that the PPU just has very hard primers.

Peace favor your sword,
Kirk

[lilmule]

Wolf mot only has heavier slide springs to reduce recoil but trigger pull as well and a complete 3 spring pkg they also have heavier hammer springs so once reduced can bring back the hard strike with less pull.
I prefer S and B or Fiochi to priviI just purchased a pa63 and someone already had done all that,while not as strong as a p64 or cz70,still on the stiff side as made,mostly due to the hard russian primers they used.

[lklawson]

Wolf mot only has heavier slide springs to reduce recoil but trigger pull as well and a complete 3 spring pkg

I don't see them on their web page.  Not for the CZ-50 or CZ-70.  I see their extra power Magazine Springs but not hammer springs or recoil springs.

http://www.gunsprings.com/Semi-Auto%20Pistols/CZ/50/

Maybe I missed them somewhere on the Wolff page.  Where did you see them?

they also have heavier hammer springs so once reduced can bring back the hard strike with less pull.

A heavier (stronger) Hammer Spring means a heavier trigger pull.  It has to go lighter in order to make a lighter trigger pull.  That's why I trimmed the length of the "New Old Stock" Hammer Spring: to make it lighter.  I just trimmed a wee bit too much.

I prefer S and B or Fiochi to priviI just purchased a pa63 and someone already had done all that,while not as strong as a p64 or cz70,still on the stiff side as made,mostly due to the hard russian primers they used.

yup.  <nods>

Peace favor your sword,
Kirk

[lilmule]

Yeah your right ,they include 3 extra heavy firing pin  springs with the recoil multi  pack.
So recoil spring heavier,trigger lighter then firing pin spring heavier if Im reading it correct.3 springs not 2,one to reduce recoil,one to reduce trigger pull and one that may or may not bring back the hard strike.

The shortening method is supposed to work but ugh to much.could try building it up with a washer dunno.
Stock sping is 9 bucks 3 pak is but 18 and different pds ea.
That P 64 I bet packs a wallop both ways.Im satified with my da pull on the pa63 while tuff can fire at close range,but would pull it off long range therefore would do as they did if have time fire it sa if long distance to call home.
Limited supply for 9x18 locally got fiocchi 95 grain fmj,does ok in it About 219 fpe ,more than the average 380.
On a side note getting harder and harder to keep the monkey at bay,com block pistols are addictive,saw a Makarov for 250 while buying ammo had to pry myself away.Ap66 sitting next to it.Drool

[lklawson]

Yeah your right ,they include 3 extra heavy firing pin  springs with the recoil multi  pack.

I still can't find the Wolff brand recoil or hammer springs for the CZ-50/70.  All I find are the Magazine springs.  They have them for the P64, PA-63, CZ-52, and several other handguns we've discussed, but I can't find them for the CZ-50/70.

The shortening method is supposed to work but ugh to much.could try building it up with a washer dunno.

Which is exactly what I did.  Seems to work but I consider it a kludge.

On a side note getting harder and harder to keep the monkey at bay,com block pistols are addictive,saw a Makarov for 250 while buying ammo had to pry myself away.Ap66 sitting next to it.Drool

Tell me about it.  I have 9 or 10.  :P

Peace favor your sword,
Kirk

[lilmule]

If you go to wolf springs often that is all you find yet sometimes a link from elsewhre gets you on a page from wolf that has them or suppliers like midway that have them example
http://www.midwayusa.com/find?userSearchQuery=cz50+hammer+spring that link one has to look at dozens to find one for a cz70

Can buy the whole 3 spring kits for about 19 bucks,from jobbers or wholesale outlets
wolf also makes long springs of stock springs one like a gunsmith can cut you wont find them in the wolf online page easily except via  a link from elsewhere-kinda odd way of doing business but sell more to smiths than common folk
I Have even found crvena zestava model 70 mags-they imported about half without mags,now looking for a cheap pistol thats useless not wanting to sell mags.Its out there if one looks hard enough.
 Baby tok I see in my future.

[lilmule]

https://www.apexgunparts.com/product_info.php/cPath/67/products_id/696
has stock hammer spring
mostly stock
https://www.buymilsurp.com/index.php?main_page=advanced_search_result&search_in_description=1&keyword=cz50

again stock
http://www.tdwsales.com/page/page/248735.htm

http://www.gunpartscorp.com/catalog/Search.aspx?catid=0&filter=202740

I can no longer find links to a calibration 3 pack yet they made it-wolf

[lklawson]

If you go to wolf springs often that is all you find yet sometimes a link from elsewhre gets you on a page from wolf that has them or suppliers like midway that have them example
http://www.midwayusa.com/find?userSearchQuery=cz50+hammer+spring that link one has to look at dozens to find one for a cz70

Sorry, but it's not in there.

Its out there if one looks hard enough.

Yeah, they're out there, just not from Wolff.

Baby tok I see in my future.

Those look like fun.  :)

Peace favor your sword,
Kirk

[lklawson]

https://www.apexgunparts.com/product_info.php/cPath/67/products_id/696
has stock hammer spring
mostly stock
https://www.buymilsurp.com/index.php?main_page=advanced_search_result&search_in_description=1&keyword=cz50

again stock
http://www.tdwsales.com/page/page/248735.htm

http://www.gunpartscorp.com/catalog/Search.aspx?catid=0&filter=202740

I can no longer find links to a calibration 3 pack yet they made it-wolf

Yeah, I'm familiar with the New Old Stock springs.  That's what I bought to trim down.  I don't recall if it was Numrich or Buymilsurp (think it was Numrich).  But I'm not terrible worried.  I still have the unmodified original spring.  I have the New Old Stock spring I trimmed down and have now shimmed with washers (which works reasonably well).

I know that I could have a custom spring wound for it, should I want to invest those kind of dollars.

If push came to shove, well, it's just a compression coil spring after all.  There are, doubtless, thousands of springs that are fairly close which could stand in for it in a pinch.

Like I said though, I'll just buy another New Old Stock spring and trim it down a bit less this time.  :)

Edit:
OK, I just rummaged through my Numrich order history and I definitely ordered the New Old Stock through them.  Will probably do so again.

Peace favor your sword,
Kirk