Nice Crip.
I'm pneumatic by nature.
I had to dig out my Benjamin Model 310 to see excactly what the model # is. 177 cal and it has dispatched many, and I mean many, critters over the past 30 some odd years. I'm not sure where my gun falls in the quality area but it is deadly. It is by far the best Xmas present I ever got. Ranks above shotguns, flyrods and golf clubs. I don't know how many hours I've put in behind the trigger but they are best memory's.
Just now when I got it out, it pumps but won't hold air or build up pressure. It's been in my closet for at least 10 years but after reading your post I want to get it going again. Any ideas?
SIO3