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 ?
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