Saturday, June 09, 2007

Finally! Guided Gun Tour #1

CZ-75B Compact, 9x19. Date of production 1997.

This was my first gun ever, and the one I've shot the most of all of them. Now, before we proceed with photos just bear in mind the gun's still a little oily and is picking up dust and lint, and that does show in the photos since they're supermacro and so close.

Firstly, I tend to closely inspect everything before I clean it just to make sure that when I'm brushing, flossing, etc. that a part's not going to fall off that I won't notice. Well, I've noticed that the fire control insert wobbles a bit... the hole for the safety "pin" are hogged out a bit.

The following two photos are safety on/hammer back, first with trigger released and second with trigger tension. Notice the gap between the insert and the frame closes up, by a measured ~.0025 inch.




Disassembled:


As you can see the CZ75 uses "Browning" style barrel lugs inside the slide ahead of the ejection port.


The barrel disengages using a modified cam action, using the slide stop pin as a lug. Note that the track is fully enclosed; this serves to completely control motion in both disengagement and engagement as well.


The CZ75 9mm chamber isn't fully supported but is very close. Note the protrusion above the chamber; I have not figured out the why but my best bet is that if you have a case head rupture that will serve to keep gases and debris from travelling upwards, i.e. into the shooter's face.


The extractor is simple, external with a pin pivot and a coil spring ahead at the front.


Here at the breech we notice two things; the extractor is set up for controlled feed (large control surface, ramped on reverse from the bottom) and you can see the notch for the protrusion we saw above the chamber. Rails are "internal", cut into the inside of the frame and the outside of the slide. Note the "divot" on the bottom of the rail on the left, this is for disconnection purposes. The trigger bar serves as the disconnector.


Here is the complete fire control insert (CZ's terminology is probably different). You can see the "hump" on the trigger bar that matches with the divot in the slide, again for disconnection purposes. Moving up you can see the ejector, the tumbler for the safety... ok, this is probably a bit hard to describe that way. Let's try this; see th ecoil spring dead smack in the middle? The piece immediately above that rolls towards you when you pull the trigger. Underneath is the sear interface; the leg on the right rolls downward and is stopped by the safety tumbler when it's engaged. The leg on the upper left moves up under trigger press and disengages the firing pin safety. Just ahead of the hammer you can see the half cock notches.


CZ provides a witness (witless) mark that makes assembly and disassembly easy.


Under the grips, we have the brake spring and the main spring and strut. Very simple stuff. CZ sells a flat brake spring so mags drop free, otherwise that leaf of metal "brakes" the mag and you have to pull it free. Grip profile is reasonably simple and I may try making my own sometime.


And there you have it; the prototype guided tour that I want to do for every gun I own.


This CZ compact is a steel framed model and is heavy, but small, about the size of a Sig P239.


CZs are rather slim in slide profile thanks to the rails being inside the frame. It does carry like a smaller gun.


And here's the prerequisite "what I carry" shot. Yes, that's a classic Motorola alpha pager, someone thinks I'm important.


In the future, I'll figure out what to do about having a light box; these were the best I could do using an overhead 100W. I should probably also wait a few days after cleaning to get the "loose oil" spread around and not so sticky to lint and fluff. A tripod would be handy as well.

Next up: The CZ-52. When? Beats me, whenever I get to it. I want to make at least one of those improvements to my method first, and I also think I want to think into these a bit so they aren't so random.

2 Comments:

Anonymous TD said...

You're letting me down, Doc. I wanted to see it stripped to the bare frame! :-)

8:59 PM  
Blogger Mulliga said...

Nice report. While I too would have liked a comprehensive detail strip, it isn't the easiest thing in the world to do with a CZ-75, especially compared to a GLOCK. I still have nightmares from when I had to replace the trigger spring on my 75B (used a knife to cut down a thumbtack to use as a slave pin - ulgh).

6:10 PM  

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