EU Polyether Urethane 90 Durometer O-Rings

[Northern Raven]

I’m pretty new here, just got my first PCP air rifle a few weeks ago.  Been having a lot of fun making small upgrades and modifications to my new rifle.
Added QD mounts and a small rail to the stock, bedded the action, felt bedded the pressure cylinder.  Polished the barrel, hammer, trigger, pellet probe, just about everything… lol

While bleeding the pressure cylinder to port and polish the poppet valve I blew the O-ring seal.  I remember from paintball in the late 90’s replacing rubber rings with urethane based ones.  Probably going to need to chamfer the inside edge of some of the grub screw threads before changing out the rings.

Any experience doing this to your air gun?  Changing out rubber for urethane.

I’ve got the JTS Airacuda standard it came with extra rings and it’s back up and holding pressure.  Already ordered the Urethane rings.  Very impressed with JTS quality overall.

[nervoustrigger]

Firstly, welcome to GTA!

Regarding O-ring material choice, polyurethane is perfectly good for PCP use but is only beneficial over the more common Buna-N for dynamic seals...those subject to abrasion like a bolt or breech seal.  Also bear in mind polyurethane has the shortest shelf life among the common types used for airguns.

[kbstingwing]

What he said, no real benefit from urethane,  Buna nitrile works best for most applications,  I find that urethane hardens after a year or two.

[Northern Raven]

Putting the ring in the brass thimble was quite a pain, material was a lot stiffer than what was in there.  When they go bad I’ll most definitely be putting the original rings back in and ordering Buna-N replacements.

Hours of entertainment for ten bucks though, learned a thing or two.

Thank you for the welcome and the info.