Are you using the factory guide rod? According to what I have read, you can go up to a #22 lb. spring....but most get a full length metal guide rod, and you should have a spacer in there...some get a cz-75 spring, and cut off three coils.....cuts down the recoil also.

Jackash Custom.....

Originally Posted by berettabone

Are you using the factory guide rod? According to what I have read, you can go up to a #22 lb. spring....but most get a full length metal guide rod, and you should have a spacer in there...some get a cz-75 spring, and cut off three coils.....cuts down the recoil also.

Installed a Wolff 20# spring, ran 100 rounds, couldn't see much distance difference in flying brass, or recoil. However had one FTF probably due to the quick return of the stronger spring. Re-installed the factory ??# spring, will avoid shooting where I can't find my brass. Unless necessary.

Originally Posted by berettabone

...[S]ome get a cz-75 spring, and cut off three coils.....cuts down the recoil also.

Assuming that both springs are the same length, shortening the replacement recoil spring will make the slide batter the frame or, otherwise, destroy any spacer that has been added.
Furthermore, it will make strong ejection even stronger.

I'm not sure that this is a good idea.

Assuming?

Originally Posted by Steve M1911A1

Assuming that both springs are the same length, shortening the replacement recoil spring will make the slide batter the frame or, otherwise, destroy any spacer that has been added.
Furthermore, it will make strong ejection even stronger.

I'm not sure that this is a good idea.

Yeah, "assuming."
I do not have first hand experience with either gun mentioned (CZ40, CZ75), so I can make only very general observations.

So if it sounds to me as if it could be a bad idea, I feel that it's my duty to write something that makes note of it.

If you go to the Original CZ Forum, you can probably glean some valuable info, some of which I stated previously.

Originally Posted by jm38

Installed a Wolff 20# spring, ran 100 rounds, couldn't see much distance difference in flying brass, or recoil. However had one FTF probably due to the quick return of the stronger spring. Re-installed the factory ??# spring, will avoid shooting where I can't find my brass. Unless necessary.