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kneelingatlas

CZ75 Open Sport

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This project is getting exciting now!

2012-10-10_20-13-34_927.jpg

My 9mm SP01 slide arrived in the mail today and I test fit the barrel and the slide on the gun:

IMG_20121010_203831.jpg

The .40 barrel from my TS slide drops right in and locks up just a tight as the TS, but the new 9mm barrel needs a little trim before it will lock up in either slide (I guess they leave the webstore a little big to be cut to fit). Please excuse the cell phone pictures, my digital camera is at the office, but rest assured, this tread will be filled with updates.

Edited by kneelingatlas

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So, I fit the barrel to the slide last night, but I ran into a problem: the SP01 uses a skinny hammer like a 75B, not the fat hammer like the TS, so I decided to install the hammer from my 97B in my Tactical Sport (just temporarily to try things out). I took both guns apart, pounded out the disconnector pin and installed the 97B hammer into the TS, everything was working well until I put on the slide; apparently the difference in the hooks on the hammer is significant enough that with the trigger bow riding on the underside of the slide it just barely misses the sear. So just about the time I was giving up on that idea and putting the guns back together, I had an idea: my local range has a 75B in the rental rack and as a member, I get free rentals! So the range rented me this test mule:

2012-10-11_11-38-52_424.jpg

I fired 100 flawless rounds through the gun and even with the stock DA trigger of the rental mule, I was able to post this ten shots at ten yards after I got it sighted in:

2012-10-11_12-01-24_134.jpg

So now it's off to the machine shop to have the barrel threaded for the comp.

My idea is to use the test mule again to try out the upper with the comp before I do any irreversible mods to my TS or my SP01 slide. When I'm happy with the upper (comp installed) I plan to mill out the notch in the back of the slide wide enough to accept the TS hammer and if I like shooting my new Open Sport I'll cut back the dust cover to match the face of the comp, machine the front of the slide, for a cleaner looking index with the comp, knock off the sights, install a slide racker, then mount a Quinn III and C-more, maybe a frame reduction before I refinish it in black. Good times ahead!

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2012-10-29_13-17-33_999.jpg

Three ports may be too much for Minor loads... The comp seems to make little/no difference shooting 115 grain 1,100 FPS factory ammo. Any suggestions?

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2012-10-29_13-17-33_999.jpg

Three ports may be too much for Minor loads... The comp seems to make little/no difference shooting 115 grain 1,100 FPS factory ammo. Any suggestions?

You need a hotter load to get the comp to work and a lighter recoil spring.

Comp needs gas pressure and volume to work properly.

Slide wl need a spring that is significantly lighter than tge standard gun

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Alright gentlemen, time for an update:

I've drilled and tapped the frame for a C-more mount/thumb rest and swapped the three port comp for a two port 9mm (the three port turned out to be a .40 comp with .4125" exit holes!) A friendly Czechmate shooter sent me a sample of his 9Major loads which work pretty well with the three port comp, although I can tell I'm losing a lot of gas out of the big holes. I'll be shooting with the dot for the first time tomorrow so I'll post my reactions, but for now here are the pics:

IMG_20130206_191010_048_zps342ce947.jpg

IMG_20130206_190952_436_zps4669d807.jpg

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Mmmm.. your thread gave my wife some ideas for her CZ Limited pistol!

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Oh yea, I left you hangin'.

I shot a steel match with PMC factory ammo and it shot surprisingly flat with the two port comp pictured above, the dot feels like cheating! I'm working on a slide racker as it's a major PITA to clear a jam when you have to pinch the slide between your thumb and index finger; I had one jam from a round jumping up through the feed lips and sticking straight up. I have since traded two 40 mags for 9mm mags, my big stick also arrived from CZ USA yesterday!

When I saw a post on here for SPP in stock at Cabelas, I jumped all over it like a hobo on a ham sandwich and bought 20k, which has served me well as currency for trade, I traded 600 primers for a pound of HS6, then scored some 124 grain CMJs, so as soon as my buddy bolts down his 550, I'll be in business. I can't wait to test some Major loads.

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What comp is that, and what is the thread pitch?

The comp in the picture above is a two port steel Tanfoglio small frame part with a thread of M14X0.75, in my obsession I have picked up more than half a dozen comps, so I've got lots of info; feel free to PM me with any question.

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How did you mod the slide to get the barrel and comp out?

I really want a TS based Open gun, but I'm not a big fan of the Czech mate and its complete lack of options. Maybe this would be a better way.

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Update: I'm still messing with the comp.

IMG_20130505_211009_284_zps08304186.jpg

I've decided 115gr bullets with lots and lots of powder are what's best here, but I'm not quite happy with how flat it shoots with the three port aluminum comp I got from Numrich:

AluminumThreePortComp.jpg

I've done some mods I'll detail later when I have more time...

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So the only off the shelf three port comp which would work for this project is for .40 and has holes which measure .4125", pretty loose for 9mm. Coincidentally 1/4" schedule 40 steel pipe has nearly the same ID/OD of a 9mm TS barrel, so I drilled out the holes in the comp, tapped them, and red loctited in a piece or pipe. I then used a ball end mill bit to re cut the ports (made the first one a little bigger too).

IMG_20130920_205204_799-1_zps101f8699.jp

IMG_20130920_205148_229-1_zps02e092f7.jp

IMG_20130923_055522_792-1_zps3a93d69a.jp

IMG_20130926_164334_015_zps263e0bba.jpg

While I was milling out the ports I inadvertently milled some bleeders :blush: but it actually turned out pretty well :devil:

IMG_20130926_164400_281_zps7fa8c3a3.jpg

Edited by kneelingatlas

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So tonight I got out the chop saw and got after my TS! Here it is:

IMG_20140319_223817_670-1_zpsijxbpmox.jp

IMG_20140319_223750_296-1_zpssfl6bmkz.jp

IMG_20140319_224820_505-1_zps6xg9lhhw.jp

I got my hands on a 9mm three port comp, so I have high hopes for this one:

IMG_20140319_224910_727-1_zpskj0yuhmc.jp

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