Benjamin Marauder.177

Where did this rubber ring come from on bolt of Benjamin Marauder.177. Pl. see the image attached. Is this O ring or any other seal ?

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THIS FORUM is for LEARNING and SHARING KNOWLEDGE so everybody reads and learns. That is unless that PM is KINKY STUFF like what LUBE you recommend. I can only imagine.

I PM only when I don't want to publicly say to pound it with a rubber mallet as though you are murdering while filling it to unstuck that valve.
 
I believe that is your breech O ring, I did the same on my .25 Check the o ring for damage, if no damage I used a long wooden dowel with a blunt tool and i reset it in the groove. A 1/8" dowel is approx .125" and should easily pass thru baffles and barrel. You'll find a replacement o ring at most Tru Value Hardware stores

ACE is the place plumbing and faucet section.
 
Assuming you never lubed your pellets I would leave that o-ring on the probe slide it close to the end tip almost flush lightly wrap masking tape around that probe behind that o-ring be sure it can slide back with minimal force but need at least some force so not at all tightly wrapped and use a little shoe goo on that o-ring and SLOWLY! close that bolt wait half a day and try shoot it first. The residual shoe goo will go away with just shooting the gun.