Confused about At44-10 22 cal O Ring sizes

[colorider]

I am in need of some o rings for my at44-10 in 22cal flavor.  I have searched and have only found conflicting information.
What I need are some spare breach seals (the one that goes inside the barrel) and I also need spares for the 2 that go on the outside of the barrel on each side of the transfer port.  That one has turned up the most conflicting information.  I have 2 harbor freight kits and none of them seem to fit like the factory ones.   Also, the correct hardness and material  I should be looking for (durometer), (viton, buna, nitrile etc)   I would love to avoid ordering a whole replacement kit as my searching seems to pull up expensive kits that replace the seals 1x.  Purchased 100 spare probe o rings for a few bucks on amazon.
Thanks again for the valuable information. 

[PeruvianHunter]

Uhmm I think the ID is 1/4", OD 3/8" (I will check that at house, now I'm at work)
Try to find those in Nitrile Rubber in the range of 60 to 70 durometer (80,85 or 90 are hard to push into the receiver)


Regards

[colorider]

Thank you !!!  Greatly appreciate the info.  Looking forward to the size. 

[rsterne]

All Hatsan O-rings are Metric sizes....

Bob

[PeruvianHunter]

Now at home I taked apart my AT44 just to help you out...the measures for the oring barrel are 11mm OD with 1.5mm thick and 8mm ID.






**edit: this is the photo of thickness measure


Mr rsterne was right the oring is metric.

I hope this can help you

[Rallyshark]

I believe you are looking for 8x1.5mm for the two outer barrel o-rings, and 5.5x1.5mm for the probe o-ring.  All in NBR 70.  There are some standard non-metric sizes that "can" work in a tight, but I'd stick to the metric sizes  

[rsterne]

I agree.... 1.5mm O-rings are a lot smaller in cross-section (thickness) than a "00X" series US size.... You may find a US replacement, more likely you will be asking for a leak, or assembly problem....

Bob

[jimmymc2900]

I agree.... 1.5mm O-rings are a lot smaller in cross-section (thickness) than a "00X" series US size.... You may find a US replacement, more likely you will be asking for a leak, or assembly problem....

Bob

Bob is correct, I tried to replace mine with standart US size o rings and all I got was leaks. The larger ones cut, and the smaller ones didn't seal. get metric and they work first time.

[colorider]

Thank you fellas.  Love the effort and knowledge shared on this forum.  My Chrono shows up tomorrow and I can start tinkering with this thing.  Have had it for 2yrs and it's time to start tuning it.  Have read pages and pages and am simply intrigued about adjusting the hammer spring and closing up holes on the air tank.