John,
Orings are just orings and on any well know manufacturer ( daystate, airarms,other) parts are available. Really pre-charged rifles ( most ) are very simple, even if you needed a valve stem there isn't much to making one should it no longer exist. I've personally never heard of a major brand that you couldn't get a part for today, maybe daystate 13mm parts are hard to find LOL but it would still be easy to rebuild everything just don't break the trigger housing or such and your fine. Even a Sprotsmatch GC2 can be rebuilt and that wasn't all that common a rifle.
I tried to sell a ( well okay left handed but stocks are around at $100.00) original daystate huntsman MKII , best trigger they ever made, nice walnut , bluing, brass, belonged to a national champion a proven shooter for $600 shipped. That rifle would shoot inside 1/2" at 500 every group but it was a single shot and old I guess. Esp. if you can get to a match and enjoy face to face, try before you buy there are some real jewels out there that are so far under priced for what they are, man.
It's a springer but I have a Hannel that is approaching 90 years and shoots well. Tammy has a bolt action air arms that is well over 10 years old and has never needed anything, had a career 707II for 15+ years never needed anything. Yes the O-rings do go sometime but I always spent more time repairing springers that pre-charged. I had a Titan MPT ( became Falcon) that was labeled Beeman of CA likely 1998 ? And to this day it's function is still 100% . Do be careful who you are dealing with but do not be afraid to purchase classic's they are most often found in loving well cared for homes and were never neglected trunck guns or such.
John
