Tech Question: Slide release problem

[Hellbore]

On the advice of some friends from the CZ forum, I swapped the recoil spring out of my CZ40B with an 18 pound recoil spring from Wolff Springs. They don't have a spring specifically for the 40B so I used a CZ75B spring and cut it shorter. I heard others have done this sucessfully. The goal was to stiffen the recoil spring and make the felt recoil less. I also thought this would make the ejected brass not fly so far.

The gun shoots .40 S&W, in case you were wondering. The spring made the slide harder to pull back but it still would go back all the way once I cut off some of the coils.

I also installed a lighter hammer spring, a 17 pound spring for a Sig P220 to lighten the DA trigger pull.

I went to the shooting range to test it and there was one problem. About every other clip or so, the slide release would lock the slide in its back position, as if I was out of ammo. I was not out of ammo though, there were like 3 to 5 bullets left in the clip still.

I have never heard of this happening. For now I put the stock springs back in the gun. I will have to hit the shooting range again tomorrow maybe and make sure the problem goes away.

In case it matters, I was shooting Speer Lawman 180gr range ammo.

Saturday morning I had shot the gun out in the desert with my dad, and went though about 150 bullets without a single jam or problem. This was using the stock springs. It was also Speer Lawman 180gr, but they were hollow-points, surplus bought in loose bags at the gun show.

I'm thinking the recoil spring is at fault, but how? Can anyone explain how the slide release would come up and catch the slide when a bullet is still in the clip? I'm confused.

 

[N3rday]

Well, earlier there was a post on that particular ammo, but that is just weird. Try it out with other brands/grains.

I don't logically see how that could happen...then again, I'm no expert

 

[Jim K]

Sorry, but I don't have a lot of sympathy. On the advice of friends who probably took the advice of their friends, you decided that the factory engineers were all wet and that you should go changing springs. So you not only used springs made for other guns but you cut some off here and there to make them fit.

And then you wonder why the gun doesn't work right? Better have a talk with those "friends".

Jim

 

[Hellbore]

That's OK, I'm not asking for sympathy. My gun isn't broken after all, putting the stock springs back in solves the "problem".

What can I say, CZ's are said to be undersprung from the factory. A bunch of CZ owners have installed heavier recoil springs without problems. Some of them are gunsmiths, so it's not like I'm making up half-assed mods

Wolff Springs themselves told me that the replacement for this gun's recoil spring was the 18# CZ75B spring.

At any rate, the stock springs are back in for now. No big loss, springs are cheap. Also, I'm told a heavier magazine spring will make it all work, but maybe I won't bother, since the gun shoots fine with stock springs.

 

[MoNsTeR]

The CZforum guys tend to buy into the heavier=better school of recoil springing. Which is of course nonsense. Heavier springs may reduce into-the-hand recoil, but at the expensive of increased muzzle flip.

If you're shooting factory ammo, and aren't having problems, stick to the factory weight.

 

[Hellbore]

Thanks for the advice guys. I wasn't aware of the muzzle flip issue. That's good to know!

Anyway, I really didn't replace the recoil spring based on any complaint I had with the gun... I actually thought it shot great with the stock spring so I guess I shouldn't have wasted my time trying different ones right?

I just think it's fun tinkering with different adjustments and such. If nothing else, it's a learning experience, I know more about how the gun works now than I would have if I had left it alone.

Here's a question: With the heavier recoil spring, I test-fired the gun at the local indoor shooting range. I used paper targets at 20 feet and 50 feet. The gun seemed to shoot consistently lower than I expected.

I had test-fired it in the desert and it didn't seem to shoot as low. Is it possibile that the heavier recoil spring could have made it shoot lower somehow?

Maybe I'll have time to hit the range again today with the stock springs in and see if that was it.