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CZ Open Build Theory


kneelingatlas

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16 minutes ago, kneelingatlas said:

 

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

Perfect, then I wont have to worry about it.

 

How much clearance do you have for a 9mm bullet in the comp? I assume that the comp works better with less gap around the bullet so that the gasses are forced to go out the ports.

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10 minutes ago, Johansson81 said:

Perfect, then I wont have to worry about it.

 

How much clearance do you have for a 9mm bullet in the comp? I assume that the comp works better with less gap around the bullet so that the gasses are forced to go out the ports.

 

0.375" is pretty typical for the exit hole of the comp, the bullet is 0.355" and I've heard of people who go as tight as 0.365"

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11 minutes ago, kneelingatlas said:

 

0.375" is pretty typical for the exit hole of the comp, the bullet is 0.355" and I've heard of people who go as tight as 0.365"

Ok. Since it is so short I guess an angle error of a tenth of a degree or so wont make much difference, not like with a silencer which is much longer.

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If I wanted to fit a SP01 slide with a comp to a TS frame how much would I have to cut the front end down by to get clearance for the comp? It would be nice to be able to use my TS frame for an open build as I've already butchered the grip with a DIY frame reduction.

 

Edited by TerryYu
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6 hours ago, TerryYu said:

If I wanted to fit a SP01 slide with a comp to a TS frame how much would I have to cut the front end down by to get clearance for the comp? It would be nice to be able to use my TS frame for an open build as I've already butchered the grip with a DIY frame reduction.

 

 

Approximately 0.9"

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8 hours ago, Fo0 said:

Do you need to cut an angle on the slide for the comp like on 2011's?

 

There is an angle to deal with.  Machining a comp is not as easy as it looks, the bore axis is not parallel to the frame rails, and in some pistols, the frame rails are not parallel to the top of the slide and those angles are not necessarily the same, from manufacturer to manufacturer or even from model to model from the same manufacturer.

 

For example, through a miscommunication with the machinist, the first batch of Czechmate comps I made tilt down by one degree:

 

5aa39dabd6e6d_opensport.thumb.jpg.6a360523e084c6f98e6697e5654893bc.jpg

 

For the second batch he cut the body of the comp in one step, then set up at a one degree angle to cut the cone, and bore hole.

 

IMG_20180702_212116-3527x2148.thumb.jpg.274f1c5531a6be79d55dd3299c643565.jpg

 

The top edge of the 75B SA slide, however slopes down relative to the frame rails but roughly one degree, so the comp doesn't look as funny in that pairing:

 

IMG_20180718_170756.thumb.jpg.a04e17134de9ffb403d3a2bf2215c5de.jpg

 

(Comps from this first batch are available at heavy discount on clearance ?)

 

If you look closely at some 2011 builds you can see the comp is cut with the outside edge concentric to the bore hole and when in battery the tilt down by something like a half degree, in small frame Tanfoglio compact slides, the barrel tips down by more like two degrees.

 

 

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I'm toying with the idea of stroking my open TS.  I have one with a SP01 top end and the other with a 75B SA upper.  I don't want to over do it.  Would going all the way from 1.875" to 2.400" be the most beneficial if I am going to be running a shockbuff when I get done?  Also, I have not yet drilled the front of the 75B SA upper to run a full length guide rod.  Is that something that needs to be done to stroke that upper?

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3 hours ago, aandabooks said:

I'm toying with the idea of stroking my open TS.  I have one with a SP01 top end and the other with a 75B SA upper.  I don't want to over do it.  Would going all the way from 1.875" to 2.400" be the most beneficial if I am going to be running a shockbuff when I get done?  Also, I have not yet drilled the front of the 75B SA upper to run a full length guide rod.  Is that something that needs to be done to stroke that upper?

 

The two slides you mentioned are 0.6" shorter than the TS slide, so if you stroke them that much I image you'll get coil bind using standard length springs, you might use a Czechmate recoil sping housing to lengthen the recoil system again like this:

 

IMG_20180718_170756.thumb.jpg.a04e17134de9ffb403d3a2bf2215c5de.jpg

 

2011 gunsmiths do the same thing when they build shorties:

 

post-7070-1159116820.jpg

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2 hours ago, GhostDog said:

Nice collection!

 

which one is your favourite, and why?

 

Gosh, that's like asking which kid I like best!  It depends on the day.

 

I've found the lighter, CZ75 guns get out of the holster faster, but the triggers aren't as good.  The other thing is: I've been working on softer, flatter Open guns so long, and they're all so good, it's hard to tell the difference.

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