slide/barrel/comp fitting after a failed barrel

[gianmarko]

hello everybody

has been some time and seems i need again advice from the experts here

last thursday at the EEO i broke my third barrel. second in a match, murphy's law...

 

i am fitting a 2017 barrel with the improved lug, as per instructions here

 

https://imgur.com/gallery/TMIXx

 

adjustment is almost complete, but reassemblying the barrel to slide and compensator i have again a problem: giving the comp 24 turns, i have a 0.85mm gap between comp and slide, as the thread is 1mm, if i give 25 turns the gun will not close

 

i had a similar problem when fitting a new barrel last time i had one fail around 18 months ago, and had to machine a couple tenths of mm off the comp to ensure proper coupling

 

i have checked other barrels i have (broken and good) and the number of turns of the compensator to the barrel varies between 23 and 25.

 

the other checkmate i have has 3 barrels that can be exchanged and comp will fit properly.

 

i can either machine a couple tenths mm off the comp so i can give it 25 turns and have a good coupling, or i can leave the 0.85 gap, but then i have a play between barrel/comp and slide of 0.12mm ( a bit less than 5 thou, which seems excessive to me)

 

any suggestions on how to proceed?

 

a dutch shooter told me that he had an improved lug barrel fail in his gun. seems that CZ cant solve this problem...Robin Sebo told be the new barrels dont fail but probably they still fail, maybe just less frequently.

 

this barrel failed at maybe 12k rounds. previous one failed at less than 10k

in the other CM the first barrel failed at 15k rounds or so, the current barrel has over 30k, thats why i was shooting the other CM at the match.

 

pretty annoying...

 

 

 

 

 

 

[yigal]

i prefer gap of 0.05mm-0.1mm  and not 0.85mm.  but u can use it as it is.. 

for this comp u will need  lathe and jig  with thread  M14x1  to make perfect fit.

stronger recoil spring will increase barrel lower lug life.

[gianmarko]

thanks yigal. so you think that the lateral play between comp/barrel and slide will not affect accuracy? that i can test anyway. why not.

 

last time i adjusted the comp i indeed used my lathe, too lazy to install the 4 jaws chuck but  some shimming did the job,  i removed .2 mm if i remember well.

 

 

 

some time ago i did some tests with different springs, the results should still be on this forum somewhere. i installed a position sensor on the slide and measured slide speed with different springs. what i saw is that with different springs the speed of the slide in opening does not change much, i could not measure the difference. what changed was the speed of closing, which was slower with weaker springs, obviously.

but i might give it a go with a stronger spring. i dont use very weak springs anyway, i think i am on a 11lbs  now

 

regarding the slide lock pins, i am currently using those pins coming from an ingersoll rand impact hammer (p/n 2112-704). they seem to last a bit longer than the standard pins, but they also break. i think they l;ast 7-8000 rounds, but they are cheaper than CZ ones.

 

Robin Sebo was selling some different pins, cheaper than CZ at 12 euro, got a couple of them and will test them

Edited June 25, 2019 by gianmarko

[yigal]

don't forget the  change in the speed 

[my00wrx1]