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kneelingatlas

CZ Open Build Theory

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The other thread is full of broken picture links so I decided to start a new one here.

 

When planning a CZ Open build, there are a number of things to consider:

 

-comp type:  cone or bull, off the shelf or custom, aluminum, steel, or titanium.  With a bull style comp the barrel bushing remains and the comp us screwed onto a barrel at least 0.4" longer than the slide, with a cone comp, the bushing is removed and barrel lockup happens between the cone and slide.

 

-barrel length:  4.5" (standard 75/SP01/Shadow), 4.7" (Shadow 2/Australian Shadow), 5.1" (Tactical Sports/Czechmate)

 

-slide length:  if you cut the length of the slide you can use a recoil spring housing like the Czechmate:

315047000002.thumb.png.142d21dd718a3646fd917e102fb7c3c5.png

If you don't cut the length of the slide, you don't need the recoil spring housing, but you then have the front sight dovetail and the taper at the front corners of the slide to deal with.

 

-frame length:  when the slide reciprocates, the barrel/comp move back relative to the frame approximately a quarter inch so the frame needs to be cut at least 1/4" back from the end of the slide or the comp need to fit inside the frame rails.  Unfortunately cutting the frame typically gets into the serial number, so depending upon your local gun laws you may need to file official paperwork to relocate it.  A short dust cover frame eliminates this issue, but the downside of a short dust cover is that it won't cover a stroked slide.

 

slide stroke:  the stroke of a standard CZ 75 is 1.875", the stroke of the Shadow 2 is 1.890", the factory stroke of the Czechmate/TS is 2.000", the factory stroke of a 2011 is 2.115", from what I've been told, Akai strokes his 2011s to 2.415".  My custom TS Open is stroked to 2.440", then I run a buffer which gives back 0.140".  The stroke is increased by removing material here:

IMG_20180821_222128.thumb.jpg.6d9a583b219d9b69e4df08abfa232e3f.jpg

Increasing the stroke gives a longer distance over which the recoil spring can slow the slide before it impacts the frame, it also allows for the use of buffers without inducing short stroke issues.

 

-removal of the comp/barrel: unfortunately bull or cone, CZ comps/barrels are not designed to be removed from the slide in one piece like a 2011 or a Tanfoglio, so you're either stuck removing the comp from the barrel before disassembly or doing extensive modifications to the barrel and slide so it can be removed through the front:

IMG_20180324_224927141-1202x2137.thumb.jpg.583e8626c4d378c27da904af3cf253cd.jpg

 

-optic:  slide or frame mount, mirco dot or slide ride.  I prefer a horizontal CMore Slide Ride, while it's not the sexiest, and a few ounces heavier than a micro dot, it has the biggest glass and gets the dot closest to the slide:

IMG_20170706_185636.thumb.jpg.659f6c1887f527c28fe0a574c9849bfe.jpg

 

-thumb rests: thumb rests are pretty personal having a lot to do with your thumb length and preferred angle, although I like them pretty much parallel to the barrel.

 

-slide racker:  the Czechmate racker is slightly smaller than the factory dovetail on the regular 75 slides which are unfortunately larger than anything commercially available, so they must be custom made.  Because of the dovetail location towards the rear of the slide, if you want a racker on the left side (for right handed shooters) you need to cut a dovetail right behind the breech face so it doesn't interfere with your thumb.

 

-big stick mags: the best part about the Czechmate/Tactical Sports platform is the big stick, it's factory made, with CZC pad/guts it holds 29+1, and it works!  I've heard of people who need to tune these, but in my personal experience, when I first got my Czechmate, I tried to use my regular 115gr JHP load from my 2011s which would randomly nose dive out of a fully loaded big stick; I switched to Montana Gold CMJs and never had a problem since.  If this is not the case for you, I hear Bevin Grams offers the tuning service at a reasonable price.  For the standard CZ75 guns, there is no off-the-shelf option for a big stick, so the easiest thing to do is use an 18 round tube, CZC long base pad/spring/follower for a mid-length mag (~160mm) which holds 25+1.  Otherwise you can cut a Promags 26 rounder to fit the gauge or weld two tubes together.  I have a few 170mm mags I've put together which hold 28+1.

 

Those are all the issues I can think of right now, but if you can think of anything else, please commercially below.  On to some pictures!

 

Some are mine, some belong to friends, and some are just pictures I've collected over the years.

Edited by kneelingatlas

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Good info here.i picked up a tac sport 9mm milled with an rts2 that I may go this route with.

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Awesome thread and thanks for the reupload. I was sifting through all your older posts about open CZs to learn more about them and maybe build one, one day.

What do you use for drilling and tapping the frames? I see that CZC has a jig for using with their optic mounts but that is all I've found for the platform.

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2 hours ago, venture said:

Awesome thread and thanks for the reupload. I was sifting through all your older posts about open CZs to learn more about them and maybe build one, one day.

What do you use for drilling and tapping the frames? I see that CZC has a jig for using with their optic mounts but that is all I've found for the platform.

 

I measure out the first hole, use a center punch to make a dimple for the bit to grab, drill it with my drill press, replace the drill bit with the tap, turn the chuck by hand to tap it (using Tap Magic oil), then use the mount to lay out the other holes, center punch them and repeat.

 

The CZ frames are pretty easy to drill when compared to Tanfoglio which is pretty much impossible without annealing first.

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How hard are the CZ barrels? Will a quality threading die do or do you need carbide tipped tools in the lathe to cut the threads?

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2 hours ago, Johansson81 said:

How hard are the CZ barrels? Will a quality threading die do or do you need carbide tipped tools in the lathe to cut the threads?

 

I use cheap M14X1 dies from China off eBay, they cut nice threads.

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