CZ75 chamber shape vs other guns chamber shape

[dabljues]

Hi,

This is probably gonna be the most retarded question I ask on this forum (hope I'll not get banned for the sheer stupidity of having to ask it), but this is something that I was wondering about for a long time.

I'll cut to the chase. I own a CZ TS2. Love the gun. I made a habit of press checking it whenever I chamber a round. And the press check is really easy to do - pull the slide, see the brass, let go of the slide. When I try to do this on my other guns (CZ P-07 or Sig P320 for example), sometimes the chamber "gets stuck" on the slide. I have to give the slide a little push from behind, to it goes fully into battery.

Now, from what I understand, this is because of the chamber shape and how it sits in the slide. In TS2 (or other CZ75 variants or 1911 for that matter), the chamber is round:



It sits "inside" the slide, like this (the top of the slide partially covers the top of the chamber):



This makes the racking of the slide/press checking much easier and smoother. Additionally, it looks like it makes the barrel "tilt less" (I know that the CZs that I'm talking about, and 1911s for that matter, all have a titling-barrel mechanism - but on 1911s and CZ75s the barrels tilt way less thatn on something like a P-07, Glocks etc.). I also know that there are different locking lugs here (the CZ75 has this "kidney shapped" doodad), so maybe the barrel tilt differences are because of that, but I'm not sure.

On handguns that have the "blocky" chamber (excuse my lack of professional terminology), like this:



the chamber kinda stick out, is not covered by the slide from the top (as there's "no slide" on top):



so, when racking the slide, the chamber has to first "go under" the back portion of the slide.

What I wanted to ask is: why pretty much all the new guns that are not variations of either CZ75 or 1911 (or some other older designs) have this "blocky" chamber? Does it have an advantage over the "round" one? Because I personally can't find any, beside it actually having one disadvantage - less smooth to rack the slide/press check. Additionally, the guns that have the chamber partially covered like that look cooler to me. As I mentioned, this doesn't only apply to CZs, 1911s and other older designs are the same, but I thought the question still could be asked on a CZ forum.

P.S I tried googling the answer to my question, but I didn't know what to google. "Round vs blocky chamber" searches brought me "should I carry with round in the chamber" results.

[M1A4ME]

In my experience (own several brands/calibers of pistols) that little hesitation right before complete/total lock up can be due to a nice snug/tight fit between the barrel, the slide and the locking lug up front in the frame.  The results are usually a better shooting pistol. 

You'd never see that drag/hesitation/need to push the slide forward when the slide is moving from firing or from a slide lock magazine change/reload.

Why do you do a press check?  Do you carry it around in the holster unloaded sometimes?  I have some CZ75 type pistols but don't carry them.  I do carry a P07 all the time and I can see the brass in the cylinder by looking at the slide/chamber end of the barrel without having to move the slide slightly to the rear to confirm there's brass/cartridge in there.

I have an M&P 2.0 .45 acp that has to have the slide pushed forward if I ease the slide forward instead of letting the recoil spring drive the slide forward without impeding it by holding on to it.  It is also a better shooting pistol than any of my full sized 1.0 M&Ps or my 2.0 9MM when it had the factory barrel in it.

The only chamber issue I've heard of with CZ's over the years is some of them have internal chamber dimensions that can lead to problem chambering some ammo.  Different bullet shapes and cartridge over all lengths can cause problems in some CZs when that ammo works great in other pistols.  And sometimes you run into CZs that will chamber ammo just fine that other brands won't.

[dabljues]

Why do you do a press check?

It's a habit of mine. I don't usually carry a gun (if I do, it would be a P-07 as well). I do press checks simply when chambering a round on the range, nothing fancy.

The only chamber issue I've heard of with CZ's [...]

It's not an issue for me. I was just wondering why some chambers are "blocky" and some are "round". Because for me, the round chambers (which are covered by the slide from the left and from the top) are just slicker to press check and they don't cause the barrel to tilt as much when the slide is locked back. So, nothing wrong with the P-07 chamber for example, I'm just wondering why is it different than the CZ75 one, are there any benefits to that (because most of the guns I see have it - all the polymer wonder 9s etc.)?

[Crawl]

What you're describing is the mechanism by which each pistol design locks into battery. There may be others who are able to describe it better.

You'll notice that on the older designs that use the rounded locking lugs like the 1911 or CZ75, there is a barrel bushing to help lock the barrel into the same position each time it goes into battery.

On the newer designs like the P-07, the lockup is achieved using a square locking lug which is the front edge of that blocky area around the chamber. This eliminates the need for a barrel bushing because the lock up is controlled better by that lug surface.

There may be other reasons, but as far as I know, it's a cheaper way to achieve acceptable accuracy and reliability.


Edit:  There may be others who are able to describe it better.

[dabljues]

There may be able to describe it better.

Yeah, you described it better. And what's more important - in a quicker manner

Yeah, I noticed the stuff you're talking about. On my CZ TS2, the barrel sits tight in the slide - visible from the front. On my P320 the barrel "cutout" on the front of the slide is larger that the barrel diameter, so the barrel kinda rests on the bottom of it. Kinda visible here:

There may be other reasons, but as far as I know, it's a cheaper way to achieve acceptable accuracy and reliability.

That was also my thinking. So, I'll still claim that the rounded locking lugs of the CZ75/1911 make the slide easier to rack/press check. It's just overall smoother feeling. And the looks are better IMO. Less chunky, more slick

[Crawl]

The additional space between the muzzle and the slide could also be something that increases reliability when it's dirty because there's more room for blockages to fall out (mud, water, sand, ice, etc.) and because there is a greater tolerance for something to jam it up.

[dabljues]

Yeah, that's also true.

[SI VIS PACEM PARRABELLUM]

The additional space between the muzzle and the slide could also be something that increases reliability when it's dirty because there's more room for blockages to fall out (mud, water, sand, ice, etc.) and because there is a greater tolerance for something to jam it up.

There is no space between the muzzle and slide on a bushingless barrel such as the P-series CZ's. Once the barrel is locked into battery the bottom of the muzzle is held tightly against the lower front of the slide.There is a gap at the top of the muzzle but not the bottom. This causes a very tight repeatable lock up of the barrel.

[Crawl]

My age-old method is working! Say it wrong so that a better-infirmed individual will correct me. Haha, thanks for the assist.

Does a bushing barrel not have a tighter lockup of the muzzle than the P series?

[Wobbly]

All these guns, regardless of chamber bump size, use the John Browning method of tilting the barrel to assist the round going into the chamber AND lock the slide when in battery.

If you experience ANY difficulty chambering a round, then the first step is to check the ammo (not the gun). Read more about it here:
https://czfirearms.us/index.php?topic=21462.0

With the CZ and several other Eastern European handguns, the chambers are cut for FMJ and the freebore is not generous. This means many American specialty bullet designs can keep the gun from going fully into battery.

I'm not saying that is your problem. What I'm saying is that it is a common issue 1) when using fancy hollow points and other bullet shapes which they don't have access to in Europe, or 2) handloaded ammo where the OAL may be too generous, or 3) both of the above.

>> If this is what your testing reveals MAY be an issue, there is a LOT more help for BOTH ammo buyers and ammo handloaders in the "stickies" of the Ammo & Handloading sub-forum.

Hope this helps.

[dabljues]

@Wobbly

Thanks for the information! I've read some posts on the forum regarding this issue (i.e. CZ's notorious short throat). But this is not it

The thing is - I'm not describing an issue. I'm describing a difference. I made a short video. You can see how my M17 stacks to my TS2 (both cartridges are dummy rounds, but made out of brass and real bullets - no powder, primer is rubber):

https://i.imgur.com/vflNo9g.mp4

(here's the link if the embedded video doesn't work: https://imgur.com/a/KUYGL6A)

So, as you can see, racking the slide on the Sig - no problem. As soon as I get a round there - press checking becomes hard, clunky. Either I don't use enough force - I cannot really see the brass clearly, the operation is not smooth or I use too much (not shown on the video) and the round will extract. Additionally, there's a point where the chamber will even hang on the slide, needing a lil' push. This is what I saw people doing on their Glocks (when press checking) etc. Sometimes, if I'm "lucky" I can recreate this hangup even without a round in the chamber (by gently playing with slide). So this is nothing out of the ordinary, I consider it just how those types of chambers/locking lugs work. Same would happen on my CZ P-07, same thing I saw happening to many people. Nothing serious, just tap the slide from the back and you're gtg.

In the case of CZ - nothing at all. With or without the bullet, buttery smooth. And that's why I made this topic - if the chambers/locking lugs like that CZ has cause the slide racking to be smoother, gun easier to press check etc, then why all the Glocks and other moderns guns use those blocky, clunky chambers/locking lugs? I've got one answer - it's cheaper. And I can accept that. I just wanted to know 

[Crawl]

Thanks for not posting the one where you shot a hole in your hand. Holy flag staff, batman.

[M1A4ME]

I know a guy who had the habit of putting his left hand in front of the muzzle to push the slide back.  I warned him about it and he argued with me and kept doing it.  One night he put a .40 S&W 180 grain hollow point into the palm of his left hand that exited up near his left elbow.  Lucky as hell it didn't hit a darn thing important.  Just traveled between the skin and muscles and caused some bleeding and one really shaken up guy.  Don't know if he learned from it or not, but he did blame the pistol and sold it.

Scary.

[dabljues]

No live ammunition was used during the production of this movie

[SI VIS PACEM PARRABELLUM]

Does a bushing barrel not have a tighter lockup of the muzzle than the P series?

Depends on how well the bushing is fit. I honestly don't find my P-series CZ's to be more accurate or less accurate than my 75 variants which are bushed. 1911 guys know a loose bushing affects accuracy and one fit too tight can affect reliability so the balancing act of fitting comes into play. The bushingless barrel desing allows for cheaper manufacturing cost by not having to install and fit a bushing and it does provide a very tight lock up since as I said before the barrel is forced tightly against the slide so when the slide is in battery there's actually no movement at the muzzle.
Pretty much everyone today has moved to the bushingless design.