Walt Sherrill said:
I disagree, but would love to hear a more technical explanation of why I might be wrong...
I don't think the extractor really knows whehter the slide is moving faster or slower; the extractor will be applying the SAME FORCE against the case rim with either recoil spring when gripping the case, regardless of the recoil spring used. If you can explain how SLIDE SPEED affects extractor function, I may be able to agree with your explanation of the solution.
I'm sure you're aware that there's a lot of pressure inside the case and this causes it to expand and press up against the walls of the chamber.
That's why you have a resizer die for reloading, to return the expanded case back to it's proper diameter after firing, because it expands when fired.
When the case is still hot from the burning gases and pressure it is at it's maximum diameter and pressed tightly against the chamber walls. Give it a few fractions of a second and a naturally malleable metal like brass will bounce back and try to come back to it's original size.
If the extractor doesn't care about slide velocity then why does it rip loose from the rim in the first place?
Yes indeed you have the "SAME FORCE" being applied by the extractor, but if the slide is moving faster then there will be more force to pull the extractor loose from the rim than on a slower moving slide. Any time you apply a fast sudden jerk you are more likely to pull something loose than a slow steady pull.
If the case is moving rearward at the same speed from the pressure there's no way the extractor will pull loose.
The original poster DID try a heavier recoil spring and the problem wasn't resolved.
Well in my case just changing the extractor spring didn't cure the problem. It helped. FTEs went from every other mag to maybe one in a 100 rounds but they still happened, after using a new recoil spring as well they stopped and I haven't had once since. Just changing one or the other isn't the answer both of the weak springs need changed.
This wasn't an experimemnt or an original thought a local smith gave me the suggestion because of problems he's had with CZ extraction issues. His idea was the slide velocity was too high due to the weak springs, and from my personal experiences I agree. YMMV
The OP also cleaned the extractor, but didn't change out the extractor spring. (He may have actually removed the extractor and cleaned behind it, removing gunk too, but that's a bit more involved, and I suspect he would have mentioned it if he had done that. (Blasting out that area with spray solvent or compressed air were the only things I found helpful until new springs became available.
Been there done that....didn't help.
I would argue that if the round isn't being stripped from the chamber, or is being dropped before it hits the ejector, it is almost certainly 1) a damaged extractor, 3) junk behind the extractor arm (in a CZ) not allowing the arm to press down with full force -- not possible with some of the clones, as that area opens into the firing pin channel in those guns -- or, 3) a weak extractor spring.
Well I did consider getting a new extractor, but tried stiffer springs first.
Glad I did because a new extractor is $40 and since changing out the springs it has worked perfectly.
If it were a damaged extractor or gunk why does it work perfectly now?
If it were just the extractor spring then why did I still get FTEs after changing it?
Wolff offered the heavier extractor spring solution first; CZ-USA sent out Wolff springs to those with extraction problems, not heavier recoil springs. They've apparently since gone to heavier extractor springs in their production guns.
I'm quite sure that the extractor springs were too weak.
As I said these early CZ and their clones had a reputation for weak springs.
So if they're using weak extractor springs what makes you think the recoil springs are any better?
As I'm sure you're aware the CZ type guns have a relatively small light slide, don't you suppose that a weak recoil spring could contribute to the problem?
I'm sure it was a whole lot cheaper for CZ to just send out new extractor springs that will usually cure the problem, than it was to also send out new recoil springs that combined with the extractor spring will definitely cure the problem. Most companies are usually looking for the cheapest solution, even if it doesn't cure everyone's problems.
A heavier hammer spring would work just as well as a heavier recoil spring, too, if your interpretation of the problem is correct.
That may well be.
I haven't tried it, have you?
It's a lot easier to change the recoil spring and it won't effect trigger pull.
It may work too, but you will wind up with a heavier trigger pull.
But I do know what worked for me and it didn't effect the trigger pull.
I didn't say to not change the extractor spring but I am saying that may not be the only problem caused by weak springs.