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Here's another blast from the past; the old GB forum, that is, from the UJ archives.

This was quite a controversial topic in it's day, and I opine that it still bears contemplation by the CZ-52 fan.

So for your nostalgic information....;

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"One thing that will occasionally happen with ammo as it ages is "adhesion" between the bullet and the inside of the case neck.

Some of the molecules of the different metals in contact with each other sort of mingle, combined with a bit of corrosion between them. That causes the bullet to "stick" in the case somewhat, and that stickiness causes elevated "pull pressure" which in turn can elevate or spike pressures.

What I like to do with X25 ammo, particularly anything older than about 1955, is to run it up into my seating die and seat the bullet down just a few thousandths of an inch to "break" that adhesion.
Sometimes you can actually hear a little "snap" as you come down on the press handle and the adhesion breaks.

A couple of years ago 3 of us here on the GB did a lot of research, and one speculation we came up with is that the chamber dimensions of the CZ-52 are not all that consistent.
Loading a milsurp round, which is typically seated longer than recommended OAL in the manuals (the few which even list X25, that is) in a short chamber is apt to result in pressure issues as well.
I figured that seating them back to 1.355" not only breaks adhesions but reduces or eliminates any risks of "wedging" a long seated bullet into the leade.

One way to check for this "Wedging" caused by excessive ctg. length, short chamber, or a combination thereof, is the "PERRY SPIN TEST", named after Don Perry who used to post a lot here 'till he got married, and that's about the last we heard from him. I hope that he is well.

Essentially, you remove your barrel and hold it muzzle-down.
Insert a round into the chamber - let it drop in, don't push it.
There will be about 1/8" of the base and rim extending out from the breech.
Grasping the exposed cartridge head between thumb and forefinger, turn it back and forth like the volume knob on a radio (the old fashioned kind before they went digital).
It should turn easily without significant resistance; that means that the cartridge is resting on the shoulder, as it is supposed to.

If the cartridge sticks or is difficult to turn, then either the bullet and/or the neck is binding in the forward part of the chamber or the "leade" which is the first part of the bore beyond the chamber.
A round fired with the bullet and/or neck wedged into the leade like that may lead to a situation much like insufficient headspace (firing slightly out of battery - not fully locked up) or pressure spikes, as more pressure has to build up in the chamber in order to overcome the increased "pull pressure" of a semi-stuck bullet. Combine the two, and things could get risky.

If you are having trouble with a certain lot of ammo, try the PST with it, then with a lot which is known to function well. See if you can feel the difference in the resistance to turning the round in the chamber.
Usually, re-seating the bullets back a bit will resolve the issue.

There are a couple of reasons why I don't recommend the Czech-O-Matic as a "Beginner's pistol", and this is one of 'em. "

 
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