If the loading port has a sharp 90° transition, it will probably continue shredding O-rings until you deal with it. Use something like a piece of 320 grit wet/dry sandpaper glued to a skewer or small dowel to break the sharp edge and then smooth it with 400 grit or 600 grit.The factory O-ring on mine didn't last through day 1. Since knocking down the sharp edge, I have probably 3000 shots through it with the same O-ring.PM me your address and I'll put a couple -006 Viton double-seal types in an envelope for you. Also, be forewarned that the O-ring on the check valve inside the fill nipple tends to extrude under the continuous exposure to high pressure. I replaced mine recently with a harder 90 durometer O-ring in hopes that it will hold up longer. I bought a whole bag so I'll send you a couple of those as well.
Right now I've got the B-50 tethered to a tank regulated at 2200psi. Insane consistency. Shot after shot at 890 fps max deviation 2 fps with the 18.13 gr JSBs.
Is the bolt o-ring on the .22 B-50 the same #006 as the .177?Mine has deformed, is loose on the bolt and is now dragging, so measuring it falls well down the list from asking here.Thanks!
Thanks all for the tips.The rifle was originally tuned by JTB530, he did a great job taming the beast. He also thought there should have been a few of the quad seal rings left in the box. A little digging and I found them.The bolt had been operating smooth as oiled glass, but then it started dragging. I figured out it was the bolt oring. I will check for any edges left that may have started this before I replace the seal.I've had the fill nipple apart already and have seen that seal starting to deform. May need to get a few of the 90s ordered for these 2 identified areas. That may even put a few fps onto what it's doing.So far, the B-50 has been a dream. Not my first pcp experience, that would be the .177 and .22 pair of FDPCPs. They are backyard friendly now and I use them for controlling pests. The B-50 is still too much of a canon for the close quarters work. But BubbaZ's FT build isn't helping me control the urge to call MM and get one of the remaining .177 B-50s.