Soft Frame

[Claual]

After many thousands (may be 17/20k) rounds the pistol accuracy is excelent with no jams at all BUT, last two range sessions I have serious news. First news has to find in the floor range piece #37 at end session; I go to home, strip, clean and build the pistol, next session the slide do not stay in rear position with  last round, I do not use +P ammo never, only soft reload ammo in the range, test then with factory ammo and carry magazine (in the range I only use one magazine, the carry magazine is clean and new) with same result, I test rack the silde with empty magazine and slide stay in rear position, I put empty case in chamber and rack again with no problem (slide stay in rear position); put five rounds in magazine and fire, with last round slide is closed.
After examinate gun in detail (I discard #25 profile), dicover seeing frame from up, that rear wide is bigger that front wide so, see pin #40 is depresed on both sides of frame; making pressure on both sides of frame I see the wide variations on frame and piece #25 movement. Concluding I believe that, at firing time frame is flexing in wide (reason for lost piece #37) and piece #25 is displaced to left impeding make stop to the slide in forward movement.
The question is, the frame material is factory soft? may be softened on the time? may be any reasom to make the frame material soft (ej. gun oil)?, any user with same problem? any idea to hardener frame on correct wide?.

Thanks.

Claudio

[Old Coastie]

First of all how have you been Claudio. It has been quite a while since I have seen a post from you. I hope all is well.

Second, if you have put 17,000 rounds through your pistol, you win the torture test prize. I doubt anyone else even comes close to that round count.

I do have a couple of questions. Have you replaced the recoil spring? If yes, what did you replace it with (factory, Wolff)?
Second question is what do you use to clean your pistol with?

Here is why I asked those two questions. In my opinion, CZ100's have very light recoil springs. When you fire the pistol the slide recoils and is stopped by the rear of the dust shield hitting the frame just forward of the trigger area. You are holding the pistol at the rear with that force going to the front of the pistol. If the sides of the frame are going to flex, it should be between those two points. A weak (factory) recoil spring will allow the slide to recoil faster than a stronger spring. 17,000 cycles of the slide under those conditions will take a toll on the pistol.
   I asked about your cleaning solvent because some solvents can harm polymer frames on pistols, especially the spray on kind. I stopped using them several years ago in favor of MPro 7. If I remember correctly, it is chlorine that causes the problem.

Try this experiment. Take the slide off of your pistol. Now push the front and rear of the frame toward each other. Can you see the frame expand out in the middle? When you let go, does it spring back quickly or does it take a couple of seconds? Just trying to get a feel for what is going on. Replace the slide. Does the frame stick out beyond the side of the slide. It should not.

I sure someone smarter than I will be along shortly to add to the discussion. Looking forward to hearing from you soon.

Good shooting,

Mike

[Claual]

Hello Mike, I don''t post any comment because all is ok with this gun, to day I dude if problem is gun or user maintenance.
I know 9 mm and 40 S&W use same spring, soft for 40 but good for 9mm, I use factory spring with my soft reload ammo (accurate say 4.2~4.6gr A2 for 124 gr FMJ, I use 3.8 powder charge); the insert blok #27, the frame front/insert and slide do not say any signal of violence and spring fly how new when I fail to build.
Yes, in rear guides section, slide movement (with no spring/barrel) need litle force but in vertical position the slide weight, self displace this.
I use any oil at my hand distance, from remington to singer, only use spray solvent (http://www.lubrilina.com.ar/) on first initial use, for bore cleaner I use Forg's formule ( http://www.frfrogspad.com/homemade.htm ) that use Acetone and I suspect from him.
Well, I don't remember how use the forum and should write this comment for second time, when select put the photo all is erased, (now, select all and copy for security).
I can try litle thread pin and nut on both sides to test this theory.



Here can see the arc in rear section.

Bye

Claudio