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
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I am following this thread. All mutants are to have an o-ring on the front face of the brass bushing that sits behind the breech of the barrel and one o-ring inside the receiver that encircles the outside of the breach of the barrel in front of the TP so as to seal the air puff. I have added a thicker o-ring in front of the brass bushing to cure a puffing issue on a Mutant.
I do know for a fact the barrels that have an angled TP were cut by Peter of TGAG. He did this to create better dynamics for the air entering the back of the pellet.
As far as the exact measurement of the back of the barrel the sits behind the TP I will have to look into that, it is a crucial number and can cause puffing if not the right length due to miss alignment of the two transfer ports.
Also there has to be special care taken when removing and re-installing the barrel into the receiver. I always put a thin film of silicone grease on the back of the barrel to help the seal in the brass spacer and a thin film around the breach of the barrel that slides into the receiver.
I myself is as guilty of this as anyone. If there is no problem with your gun leave it alone. For one, you are voiding the warranty by taking the gun apart without authorization by the retailer, and a lot of times the reassembly requires new O-rings just from the wear and tear of takedown and reassembly.
I hope that helps.
Charlie Frear
Maybe Charlie will chime in. I don’t think the barrel was removed (I did not) but really can’t tell. With the ends not blued I think the oring looks good.
The barrels the manufacture uses (czsub) are all machined the same same way for the shortys.
Everything is uniform. ..
I’m sure they sourced some cz barrels and had them fit..
Not sure what’s with the oring. But ohh well…
I have the drawing for the shorty barrels and that is what was went off of foR the listone barrels they fit nice.
So Charlie probably added that O-ring in there, since IIRC Brant said he never removed the barrel. I wonder which barrel is in his Shorty a Petr CZ or a Dimitri’s CZ ? I remember on my Cricket you have to leave a small gap in the same place to avoid POI changes at different fill pressures, so it’s probably better not to have it ?
The oring is for pure looks… the reciever has an oring already on the inside… and one at the end.
If all machining is done properly there should be no leak and there for that is just for looks
Brant so yours came stock with an o-ring in the barrel receiver gap ? I have no leaks without one and the stock Korean barrel didn’t have one either and probably wouldn’t allow one in there either.
I have no blowback (tissue) and about the same 1mm gap filled with an oring and I guess this is now considered the stock gun with kabukicrack’s.
I am loving this gun. The sparrows have learned it is safer to hide behind things from my side and if I can see a half inch I can still nail them with the consistent accuracy. 😛
I just noticed the deer mount in the photo. That was with a bow btw. lol
Pure awsomeness Sir…Please do let us know how she blast when up & running…
I am not sure if the blowback issue in my barrel (“CZ Rep Mad” sent by TGAG Petr for Germany barrel replacement) is same as Donny’s. My factory CZ barrel from RL Randy has no such issue. The problem of “CZ Rep” barrel is that the TP was drilled at wrong location – too far from the breech. Dman was kind enough to fix it for me. He has sent back the barrel and I should have it in next few days (I hope).
Endo & Donny,
Yalls blow back issues sound the same to me. I’m just taking a educated guess on this. If yall already changed the receiver oring out to a new one w/ no nicks/cuts, then it might be that the end of yalls barrels (where the back of the barrel slides into the receiver) might be machined a tad bit too much creating blow back causing air to pass the sealing oring. Or maybe the area of the oring sits in the receiver is machined incorrectly causing the same. Either way, yall can check the barrel by taking some digital calipers to measure the area of the barrel before the transfer port hole & measure the edge of the lower lip (where the gap is when you butt the barrel up against your receiver) & compare the 2 numbers to see if maybe the barrel is at fault. (see pic)…try & see…
That is normal… That Gap is on all guns…
With the understanding that my Shorty didnt have a replacement barrel. There’s a 1-2mm gap on my pistola also. I can stick my index finger nail in the gap and feel the “step down” part of the barrel and the receiver. Info from the experts above sounds best.
My CZ barrel also has a slightly larger gap at the receiver than the Korean did, it’s only more noticeable because there is no bluing on the barrel in the gap. Also my alignment set screw dimple lined up perfect with the threaded hole. I measured all the machining work against my old barrel and it’s all with in .001-.002 except the transfer port and the total barrel length which is around .010 longer. I did chamfer the inner rear edge of the transfer port because it was sharp and chamfered the breech opening edge as well with 1000. These differences don’t add up to anything at all, the machining work is good and I don’t have any air leaks. Make sure the brass piece with the breech o-ring is in and seated correctly, if it isn’t the barrel wont go all the way home into the receiver.
Donny,
My CZ barrel also has a small gap but it is less than 1 mm. I didn’t experience the leak from the “gap”. The leak can be caused by the incorrect location of the TP hole or the damage of the o-ring. I agree with Dman, check on those two things.
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Hi, Charlie:
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