Baby replacement CZ barrel
Received my CZ barrel from RL to replace my Made in Germany Barrel. Question for others who installed the replacement CZ barrels.
When I tried to push the barrel all the way flush against the back. There’s still about a 1 mm gap. I also noticed that the set screw on top does not perfectly line up center. There was a huge blow back that was coming out of the gap. If I wrap my palm around that area and shoot, I can feel a strong puff of air.
I removed the barrel and put it in my lathe to removed 1 mm from the end. Now the hole is lined up center but still a puff of air from the housing. So what I had to do was put an oring where that 1 mm gap was in the picture and push the barrel in really hard to screw in the set screw. Puff of air is gone but I’ll have to test for accuracy tomorrow.
Let me know how yours lined up. Thanks
All Replies
If you are having a puffing issue, the best thing you can do is put a little fatter o-ring in that will sit in the front recess of the brass spacer that is meant to hold that o-ring. Make sure you put a thin film on the back of the breech face along with silicone grease all around the portion of the barrel that slips into the receiver, also, while you are inserting the barrel it is a good thing to twist it on it’s way in. I have fixed one puffing Mutant this way.
As far as which barrels Peter angled the port, it seems to be limited to short’y that were not CZ barrels.
That’s it.
Charlie Frear
I have also done some extensive research to chase down the mystical puff or air
If you were to tear down the mutant block and remove the brass valve stem housing a gauge pin can be inserted all the way through thus ensuring a perfect alignment. …
Most of the time it’s a mater of the tport being drilled to far forward.
In order to fix that … best way to put it in a milling machine and redrill with an endmill. .1375 from breach end.
Or as another option for someone, like Charlie said the dremmel.. ( I actualy do a combo of the 2)
The craytex tips work great for smoothing out stuff…
What is happening is the barrel will overhang the tport on the block and that creates a direct path for the air to go at the oring. The oring can’t hold and thats how you get the puff…
But with a proper aligned tport and a Smooth path the air flows right on through and the oring doesn’t take the brunt anymore….
Hi Charlie,
Thank you for taking the time to check out the TP location. My Short Petr needs to be stretched out to a good 50 yards (which I don’t have) but at 25 yards all sorts of small vermin pests will have a new worry. Since I offered to buy a CZ (Firearms) barrel from Petr, and never got charged for the replacement barrel upon the return of my gun, I figure it’s one of those Czech Republic barrels (with Button rifling, per info from Petr).
I hope someone can test the accuracy this Czech Republic barrel out to and maybe beyond 50 yards. I was told these barrels are very good, but it would be a while before I could test that information. I’d like to know how it stacks up against the real-deal CZ barrel and the Listone barrel. A shoot-out? If the Short Petr barrel sucks hind tit, I might want to buy “the winner”.
Darryl
Okay, today I did some research on a Mutant. With the barrel removed I examined the transfer ports location in the area beneath the barrel. I found the TP barely sits in front of the brass spacer that holds the breech seal. I confirmed what I saw by forming some automotive clay bar inside the receiver where the barrel would sit, by looking at its impression I confirmed the rear edge of the receiver TP only sits a little less than one millimeter in front of the brass spacer. So if you are inclined to pull your barrel out and confirm the receiver TP is barely in front of the brass spacer, then check to make sure that the rear edge of your barrel barrel TP is barely less than one millimeter in front of the rear face of the barrel breech. If it isn’t, a little dremel work to bevel it back towards the breech face of your barrel should help it breath easier.
If you are having a puffing issue, the best thing you can do is put a little fatter o-ring in that will sit in the front recess of the brass spacer that is meant to hold that o-ring. Make sure you put a thin film on the back of the breech face along with silicone grease all around the portion of the barrel that slips into the receiver, also, while you are inserting the barrel it is a good thing to twist it on it’s way in. I have fixed one puffing Mutant this way.
As far as which barrels Peter angled the port, it seems to be limited to short’y that were not CZ barrels.
That’s it.
Charlie Frear
that’s science beyond my knowing. but 20-25 fps seems pretty good considering the type of mod.
Darryl
Well he was talking increasing efficiency rather than using more air with a bigger hole or increasing performance at the same air. The increases were pretty small from what I remember. Maybe 20-25 fps just for the TP but it added up for everything he did.
SeCoda, thank you for the link. That’s an interesting photo Ernest posted of an angle-cut air transfer opening. Reminds me of porting the heads on an intake manifold to reduce turbulence in the air flow. Perhaps this mod retains the power of the air charge just a bit longer, and makes it more uniform somehow? Interesting.
thanks again,
Darryl
PS I looked at page 2 *d’uh, Darryl!!). From Ernest: “Angle porting and enlarging the clearance around the valve stem and shaping it like a nozzle and enlarging the TP on the action is the only way the .25 to shot 75+ fpe and 50+fpe on .22. I use the alignment screw to aligned the TP.
I only put a light coating of oil on the polish naked barrel only once in 3 months and no sign of rusting. its always a pleasure to look at! :biggrinn:”
Not sure exactly all he did to the TPs. I know he polished them. There are probably archives on Talon somewhere where he even discusses the results.
Found this on a quick search. He definitely modified the shape of the ports and polished them on many of these guns.
http://talonairgun.com/forum/viewtopic.php?f=37&t=28036&p=286597&hilit=transfer+port+polish#p286597
hello SeCoda,
I was not aware of what Ernest has done in this area. Do you recall if he ever changed the angle of the barrel’s TP entrance? I don’t really understand the concept, tbh. It would be good if a technical explanation of the angle-cut could be found.I’ll try searching TAG.
Darryl
Earnest has done a lot of testing changing and polishing the TP’s with positive results but I forgot any numby’s at this point.
Charlie Frear
Charlie, are you aware of the effectiveness of Petr’s angled TP was ever being test-validated? I have some sort of barrel from Petr, but he no longer responds to my questions.
thank you,
Darryl
The CZ barrel I received from R&L is working out wonderfully. It has the small gap at the stepdown that all seem to have, and no blow-by issues. Hopefully this weekend I’ll have a chance to stretch it out to 50 yds. Again, lots of gratitude to Randy and Tony for helping to get us all back up and running again. Loving my Mutant!
:8:
Thanks for the explanation. This is very helpful and has clarified some of the questions.
Can you tell us what kind of barrel (the slanted TP barrel) machined by Petr? Is it a CZub or CZ Rep made barrel or something else?
Thanks again.
Regards,
Endo
Excellent question Endo…
Please do explain Charlie…
Charlie Frear
My Mutant was set up by an expert with the Listone barrel,,,,,No problems so far, I can stack Polymags at 48 yards, Love it.
Apples to oranges , But both my Crickets had puffs of air for a few shots before they broke in,,,,,, Turned by an expert also.
Maybe the orings just need to settle in,,,,
Just a thought.
Mike
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Charlie,
Thanks for the explanation. This really helps to clarify some of the “mysteries” that Petr created.
Darryl,
The Petr Short barrel shoots well (after polishing and fixing by Dman) and is better than the factory CZ barrel (unpolished) in my hands – so far.
Regards,
Endo