Czechmate barrel failed

[FTP_Shooting_Sports]

KA: The stock Czechmate compensator weighs 113 grams = 3.99 Ounces for your reference.

I think I am going to take a page out of the CFC Compensator design and combine the last two ports. I like his data on how the pressure drops off towards the front of the comp and a larger chamber is required (the opposite of what most comp designers have been doing). I will also have a couple of side ports put in. If nothing else, it will take some weight off the very end of the comp.

On top of that, the new barrel design will get fitted and the gunsmith is going to square the bottom of the FPS and slightly increase the stroke of the gun. I may also try a heavier firing pin spring depending on how it all ends up feeling and looking in slow motion.

The Czechmate uses a guide rod specific to that gun (Not the same as the TS guide rod) so there is no easy drop in lighter version available.

Edited December 17, 2015 by flgcwpg

[tomfturner]

Just out of curiosity would opening up the ports and mod'ing the comp take out enough weight? The other thing would be the question of pushing more gas into the comp keeping the pressure up on the "forward" velocity of the barrel, 'til the pressure lowered to a point where the rearward velocity was "less punishing" to the "camming" points?

Something like bumping up a 115 to push "more gas" to the comp, and lightening similar to the "expedition comp modification"?

http://www.expeditionfirearms.com/gunsmith/cz-75-ts-czechmate-compensator-modification/

Edited December 18, 2015 by tomfturner

[thompsoncustom]

Very interesting, I see wolf spring sells EX hammer springs all the way up to 26lb. If the weight on the end of the barrel was a huge problem wouldn't people running suppressors also go through barrel faster? Which they probably don't go through the round count most of the people on here do.

I also think that running a 26lb hammer spring would equal more muzzle rise but couldn't you just over come that by adding more gas to the comp.

What we need is someone shooting with a slow mo camera to test both ends of the spectrum like a 13lb hammer spring VS a 26lb or something.

[kneelingatlas]

What we need is someone shooting with a slow mo camera to test both ends of the spectrum like a 13lb hammer spring VS a 26lb or something.

It's already in my queue of experiments

[thompsoncustom]

Great to hear, I always planned on running a heavy hammer spring on my open gun thinking it might help slow the unlocking/slide speed and a tuned Cz with a 26lb hammer spring would still probably yeild a sub 2.5lb trigger pull.

[Vlad]

I haven't shot a CZ in a long time, mine has been in the safe for a few years, but I'm slightly amused that the older ones like mine broke slide stop pins, and the newer ones have the slide stop pin break the barrel. I'm kinda thinking the $35 pin might make a better sacrificial part

[my00wrx1]

I haven't shot a CZ in a long time, mine has been in the safe for a few years, but I'm slightly amused that the older ones like mine broke slide stop pins, and the newer ones have the slide stop pin break the barrel. I'm kinda thinking the $35 pin might make a better sacrificial part

I broke 2 slide stops before the barrel broke.

I received my new barrel under warranty yesterday and it is the newer style with a bit more metal in the area the old ones have been breaking.

For anyone that has gotten a replacement barrel do they need fitting by a gunsmith or do they drop in?

Edited January 6, 2016 by my00wrx1

[gianmarko]

today i will test a stiffer recoil spring. i dont have stiffer main springs to test for the moment

[gianmarko]

any chance of pictures of the new barrel?

gm

I haven't shot a CZ in a long time, mine has been in the safe for a few years, but I'm slightly amused that the older ones like mine broke slide stop pins, and the newer ones have the slide stop pin break the barrel. I'm kinda thinking the $35 pin might make a better sacrificial part

I broke 2 slide stops before the barrel broke.

I received my new barrel under warranty yesterday and it is the newer style with a bit more metal in the area the old ones have been breaking.

For anyone that has gotten a replacement barrel do they need fitting by a gunsmith or do they drop in?

[gianmarko]

today i will test a stiffer recoil spring. i dont have stiffer main springs to test for the moment

with the stiffer recoil spring ejection is a lot less energic. cases just fall 1 mt on my right. gun works reliably, i shot 250 rounds with no problem whatsoever.

recoil is "different" but cant tell exactly if it is better or worse. less snappy, perhaps.

[FTP_Shooting_Sports]

I did some video analysis of the Czechmate firing. It cycles EXTREMELY fast compared to a 1911/2011 style gun.

Using 240 FPS video, I can see that the stock Czechmate takes 5 frames under recoil for the slide to stop and then 7 to return to battery (12 frames). That is 5 hundredths of a second!

After stroking the gun and using a flat bottom firing pin stop, I gained 1 frame under recoil which made 13 frames total. I guess that is a decent percentage but no where near my 2011 style open gun.

A heavier spring will slow the slide under recoil but speed it up going back into battery. Which part of the recoil cycle is breaking slide stops and barrels? It's hard to say exactly.

[gianmarko]

I did some video analysis of the Czechmate firing. It cycles EXTREMELY fast compared to a 1911/2011 style gun.

Using 240 FPS video, I can see that the stock Czechmate takes 5 frames under recoil for the slide to stop and then 7 to return to battery (12 frames). That is 5 hundredths of a second!

After stroking the gun and using a flat bottom firing pin stop, I gained 1 frame under recoil which made 13 frames total. I guess that is a decent percentage but no where near my 2011 style open gun.

A heavier spring will slow the slide under recoil but speed it up going back into battery. Which part of the recoil cycle is breaking slide stops and barrels? It's hard to say exactly.

it looks like the impact of the barrel cam against the slide stop at the end of the opening cycle will in the long run break the cam, or the stop. so i think it is during opening and not during closing.

the impact occurs quite early during the slide cycle, when the cam drives the barrel down and unlock the breech. so at this stage the spring is still not very compressed and even a stiffer spring will probably make a small difference in the force of the impact. not sure what stops the slide at the end of the cycle, but i dont think is the slide stop.

a more powerful main spring might make a difference, but will also affect other things, like trigger, wear of the sears, firing pin, etc...

perhaps a different compensator can achieve better results without all the mechanical complication? how about angling the ports a bit rearwards so it works more as muzzle brake?

5/100 of a second is a very short time for humans and cheap cameras , but if i can locate a suitable sensor, i might try to rig up a logger capable of recording slide action across time. i play with microcontrollers in my free time. a 10khz sampling rate should be more than enough granularity to show speeds during the cycle. that would exactly show how things move, how fast, when and where.

actually, i could even using an accelerometer. i have one in my trick box, not sure it is capable of 10,000 samples per second, ill look it up.

this could be an interesting project....i would be surprised if this hasnt been done yet, actually...

i am surprised to hear that the 2011's cycles slower, with all the holes and slots that are milled in the slides to make them lighter. on the other side, everything is thicker and heavier in the 2011. faster cycle is supposedly a good thing, isnt it?

all the people who tested fire the CM say it flips and recoil less than the STI.

Edited January 7, 2016 by gianmarko

[gianmarko]

i checked the mpu6050 sensor i have, max G reading is 16 and 1000 samples per second. thats 50 samples for a full cycle, assuming the 5/100 of sec reported. not sure even that 16G would be enough. i might give it a try, implementation is rather simple.

a run of the mill arduino can read 10k samples per second so it will do fine, i think it can even do better with the proper code.

suitable linear transducers are difficult to find and very expensive and heavy, might try to rig a linear potentiometer and see if it can handle the speeds involved.

need to measure the slide travel, then order a suitable one. is just a couple dollars.

i think this would be interesting data, might even show differences with different loads and powders.

[sig2009]

I recently bought a new CZ Czechmate. From my research and a quote from Rob at CZ Custom the recoil spring is 14 lbs.

We believe the pistol includes a 14lb recoil spring. I compete with it
shooting major loads 168.9 PF. I've also shot Fiocchi 124gr FMJ factory ammo
which is probably not even making minor out of that pistol.

Rob Bagnato
Ghost Products Inc
CZ Custom Shop
480-969-1311

Edited January 7, 2016 by sig2009

[PRanta]

I measured 10 lb for CM's recoil spring.

[FTP_Shooting_Sports]

CZ Czech told me the factory spring is 16 lbs. They actually list a specific part # just for the Czechmate.

Edited January 7, 2016 by flgcwpg

[PRanta]

That doesn't make sense. CZ 11 lb spring has ø1.0 mm wire and 29 effective coils. CM spring has same wire but 34 coils, so it is lighter.

[gianmarko]

CZ Czech told me the factory spring is 16 lbs. They actually list a specific part # just for the Czechmate.

this actually match with the spring i bought from CZ at the EEO last year. wire is 1.1mm

but the spring that was in the gun originally is probably 11 lbs, wire is 1.0mm

perhaps CZ has changed spring. i also noticed other small differences between my CM and a friend's who bought one recently.

btw, how do you manage to communicate with CZ? i emailed them but never got any answer

[FTP_Shooting_Sports]

That doesn't make sense. CZ 11 lb spring has ø1.0 mm wire and 29 effective coils. CM spring has same wire but 34 coils, so it is lighter.

Just relaying what they told me. They felt people were breaking barrels because they were using too light a recoil spring.

Here is the part # from CZ USA http://shop.cz-usa.com/ProductDetail/315750500250_Czechmate-Recoil-Spring

[kneelingatlas]

Wouldn't you be more likely to break slides with too light a recoil spring?

[FTP_Shooting_Sports]

I was lucky enough to meet reps from CZ at the Canadian Nationals two years ago. I also have had a couple of warranty claims.

I find the breakage/spring setup confusing because we do not know if the slide stops are breaking going back when the barrel cams downward or when the slide comes back into battery. A heavier recoil spring would slow the slide under recoil but increase slide speed going back into battery. You also may be taking a couple of shots with a broken slide stop before you notice it which would also unevenly load of the barrel peanut.

I shoot with an ex CZ factory gunsmith and he built his own gun with a more complicated spring system (similar to a DPM) and he cut his own barrel from a blank and fitted everything. As a result, his slide stop shows no uneven wear (unlike every Czechmate I have seen) and he has never broken a slide stop or barrel in over 10 years.

I am now going to try the DPM system. It doesn't allow the slide to hit the frame under recoil but I don't think it does anything to help the initial camming of the barrel since the extra springs do not come into play until the slide almost hits the stops.

[kneelingatlas]

Everything I've seen indicates the slide stops break upon return to battery.

[FTP_Shooting_Sports]

Everything I've seen indicates the slide stops break upon return to battery.

I would happily break slide stops in return for the barrel not breaking. Unfortunately, it seems that both are happening. I just got the new CZ barrel with extra meat at the front, so hopefully that will resolve the barrel breakage issue.

Unfortunately, it appears that the barrel peanut needs to be fitted to the slide stop on the gun which isn't possible without a barrel blank. Right now, the slide stops show uneven wear.

[sig2009]

CZ Czech told me the factory spring is 16 lbs. They actually list a specific part # just for the Czechmate.

this actually match with the spring i bought from CZ at the EEO last year. wire is 1.1mm

but the spring that was in the gun originally is probably 11 lbs, wire is 1.0mm

perhaps CZ has changed spring. i also noticed other small differences between my CM and a friend's who bought one recently.

btw, how do you manage to communicate with CZ? i emailed them but never got any answer

Just call.

[gianmarko]

i only broke one slide stop, the stock one with hold open fitted to the gun when i bougth it.

the slide stop pins indeed show uneven wear, and it looks like they wear when the slide completes the recoil cycle, and in the point where the pin hits the corner of the cam and pulls down the barrel.

so if the pins break because of the stress caused by the slide closing, i would expect pins to break more often with a stronger spring. pins are cheap, though, and gun apparently keeps working even with a broken slide stops, at least for some time.

i dont see signs of wear in the front of the cam, where it breaks, or in the pin in the corresponding position.

so i am not sure what breaks the barrel in that place, but it is clearly a problematic spot. i heard from a tanfoglio owner that also those had similar problems in open guns, and that he used to have a complete slide/barrel/spring assembly with him when competing

next time i have a chance i will weight the slides of the CM and of my Shadow, and see the difference. slide stops last a lot longer in the shadow.

slide travel is approx 55mm, and the cam opens the breech at 9mm travel, i have ordered a 60mm travel linear pot, if i can get this rig working, will be interesting to see the curves of the slide movement with different springs.

Everything I've seen indicates the slide stops break upon return to battery.

I would happily break slide stops in return for the barrel not breaking. Unfortunately, it seems that both are happening. I just got the new CZ barrel with extra meat at the front, so hopefully that will resolve the barrel breakage issue.

Unfortunately, it appears that the barrel peanut needs to be fitted to the slide stop on the gun which isn't possible without a barrel blank. Right now, the slide stops show uneven wear.