CZ Open

[GregT]

Kneeling... If you get yours done before I do, post a few images. I do have access to a milling machine but need to pick-up a proper size ball end mill. It'll be a few weeks as there are too many matches to shoot lately. I'd like the lateral ports to be tangent to the interior front wall but pointed rearward at about 5-6 degrees -- maybe even 10 degrees, but have to be careful not to bite into the 3rd chamber wall.

Plus that, I need to 3D model the whole operation before coming up with exactly where the penetration points will intercept the exterior surface -- and of course the depth to take the end mill to without biting into the interior wall of the (4th) front port.

Gt

[kneelingatlas]

Easy there Mr. Fancy 3D modeling

This is my machine shop:

Edited July 28, 2017 by kneelingatlas

[kneelingatlas]

Today I shot my CM comp since I cut back the barrel ~1/8" and opened up the first port. Huge improvement:)

Edited July 28, 2017 by kneelingatlas

[Shotz]

Who makes a comp for a 75 B?

Assuming I can ever find a threaded barrel!!

[GregT]

Kneeling... You opened up the first port? Not the end number 4 port? How about a pic please.

Gt

[kneelingatlas]

By "open up" I don't mean side ports, but lengthening the top port. I'll work on some pictures of my CM project, but I did the same thing to the three port comps for my TS project:

Edited July 28, 2017 by kneelingatlas

[kneelingatlas]

KY GunCo just dumped this in my inbox: http://www.kygunco.com/dan-wesson-elite-series-havoc-38-super-pistol-425in-21-round-black-63892?utm_source=Newsletter&utm_medium=Email&utm_campaign=Hot

Quick, somebody buy it an let us know

[steel1212]

They've had a couple of those for a looooong time.

[kneelingatlas]

They've had a couple of those for a looooong time.

I imagine they're not exactly flying off the shelves for that kinda dough...

[BeerBaron]

wow, that's a loooong comp. 6 ports by my count.

[Rumpy]

Great pics, keep them coming!!

Edited July 11, 2014 by Rumpy

[trgt]

Today I shot my CM comp since I cut back the barrel ~1/8" and opened up the first port. Huge improvement:)

You are opening up the first port.

This thread seems to thing that opening up the last port is maybe the better path? ( http://www.brianenos.com/forums/index.php?showtopic=186687&p=2101053 )

... wondering if combining last two ports on a czechmate comp would make it 'better', based on people saying maybe that comp doesn't make full use of the gas you give it?

Edited July 19, 2014 by trgt

[kneelingatlas]

It's an interesting theory although it opposes my experience as well as the popular comps on the market, but if you try it with one of your comps and it works out I'd try it.

I was thinking more along the lines of side ports at the last port.

[trgt]

OK ... back to the point of the thread - custom open CZ ... here's my Shadow Open Minor 'Kit' -- something I can put on any of my CZ75's and play Open Minor, like I did today! Nice thing is I can swap slide and go - using all my same production stuff (holster, mag pouches, mags, ammo).

Complete Shadow Slide from CZCustom, milled for DeltaPoint Optic by Springer Precision, and Quad Porting done by Magna Port. I haven't played with it enough yet to be able to characterize how it shoots other than it is fun.

Shown modeled on a Shadow SAO lower from a CTS LS-B , as well as a SP01 Accu-Shadow lower.

Costs: $495 Complete Shadow Slide (New) from CZ Custom, $380 Delta Point 7.5 MOA triangle (various), $150 Slide Milling by Springer Precision, $260 Magna-Port Quad Port ... and 140/170 mm mags I already have for CZ75

Edited July 21, 2014 by trgt

[BeerBaron]

the ports look interesting. you've got a kind of V4 going on there.

[Akacala]

Trgt, I like that! I'm in the early stages of doing something similar, but I'm going to frame mount a Cmore instead of a slide ride. On that topic, Which Cmore scopes are you guys mounting? I'm new to the idea of open/red dots. Serendipitys or Slide rides or what?

[kneelingatlas]

Slide ride

[mike g35]

This thread is gonna cost me money.

[trgt]

Trgt, I like that! I'm in the early stages of doing something similar, but I'm going to frame mount a Cmore instead of a slide ride. On that topic, Which Cmore scopes are you guys mounting? I'm new to the idea of open/red dots. Serendipitys or Slide rides or what?

C-More Slide Ride mounted to the frame mount. Like KneelingAtlas, I like the 90 degree mount to get the optic as low as possible to the slide.

[GregT]

Hello all... Okay, I think I have the port thing, for me anyway, solved.

I took one of my Tanfoglio open guns and simply bored a round hole at the last port with the desired hole tangency to the front wall at the last port. I have a good idea of what this pistol performs like as I've shot this and another exactly like it for two years. I've really never liked this iteration of the Tanfo open gun anyway -- simply because neither of the open Tanfo's are accurate and repeatable in bullet strike at ANY distance. At 25 meters both Tanfo's shoot five inch groups and at 50 meters in any 10 shot string you may get 3-4 shots to hit the target -- so there's no big loss in whacking into these pistols.

A .3125 hole was cut into each side of the front port, re-assembled and went to the range. It must be said that the Tanfo's do shoot pretty soft in the first place but It would be pretty interesting to see if the perceived recoil and muzzle flip could be altered -- good or bad.

Here's a comparison of CZ open and Tanfo open pistols: Note the round hole in the Tanfo comp...

Bottom line, I detected no appreciable difference in the muzzle jump nor perceived recoil characteristics in the modified Tanfo comp'd pistol compared to the pistol before the lateral hole was added to the comp. It was much louder, however -- at least that is what I was told. As the shooter, it didn't sound any different to me.

There is no direct comparison that can be made other than, without mounting transducers to the pistol some how, so the perceived characteristic of muzzle jump and recoil become somewhat subjective. Anyway, the CZ's have been shot by any number of people at this point, along with me being the primary user. In both instances the CZ, even with out additional porting cuts, wins hands down with out doing a thing to the gun as far as perceived muzzle jump and felt recoil. Each shooter says, "Don't change a thing." Really a soft shooter the way it is with 115 grain bullets.

Having said this, the load should be mentioned so as to give an idea what kind of impulse is being delivered to the pistols.

Obviously, we are talking a major load for the guns:

-New 9x19 Starline brass

-Barry's 115 Grn HBRN round nose bullets

-Auto Comp, 7.00 Grains

-COL; 1.160(+.000/-.005)

-Primer; Seller and Bellot small rifle

-Chamber modified to provide .100 free bore

For me and my CZ's, this yields 1464 FPS average with a standard deviation of 5 FPS.

When I was shooting 124 HBRN's, the CZ's performed entirely differently, which, I guess makes sense and stirred my imagination to search for ways to make the CZ's feel better to me. This changed dramatically with when moving to the 115's.

Here's the pistols as they set: No changes will be made to the compensator.

Edited August 2, 2014 by GregT

[GregT]

Couldn't figure out how to add a new photo in the editing mode -- so here's the pistols in a new reply: I guess this more or less ends my idea of adding lateral ports to the CZ pistols.

Left side view:

[GregT]

Right side view: I have no idea of how to add an image in this editing mode! Sorry

Edited August 2, 2014 by GregT

[GregT]

So, another try:

[BeerBaron]

Great posts Greg. Thanks for sharing. Your thoughts about adding the side holes mirrors what Eric g said which was they made no noticeable difference so the dropped them.

Not sure I agree about accuracy though. My Eric custom v12 shoots very decent groups out of the box. Haven't taken it to 50m yet but have out to 25m. They certainly seem to group well for Eric g!

[GregT]

Hi, BeerBaron... Thanks for the kind comments!

Yah, wish my Tanfo's shot as well as yours, unfortunately, they don't. Been blasting with Tanfo's since 1993 in 9x21 and was sorely disappointed in the Eric Custom pistol's in 9mm. Both, right out of the case, sounded like a can of rocks being shaken -- but thought I'd give it a go anyway. One went back to the EAA and it came back even worse than when sent in. So didn't bother sending the second one. This alone caused me to look else where in finding something that would do less than an inch at 25 meters -- the CZ's do that.

My 9x21's each have over 100,000 rounds through each and will still shoot 2 inch groups at 25 meters(Benched) -- basically clones of the P9. Internally they still look to be brand new. Back then we where shooting 180 PF on a steady diet. I would have stuck with the 9x21's but brass, as you probably know, has been at times hard to find. Plus, I didn't care to be rootn' around after a shoot trying to pick-up only the 9x21's. I did not want to re-barrel perfectly good pistols, thus the Eric Custom buys.

Here's my 9x21's as they where retired:

I always buy in two's.

I'm not surprised that Eric G doesn't have any issues with his pistols -- more than likely there's quite a bit of money being tossed at those guns, along with top notch g'smith's doing the work.

Regards,

Gt