If you can find one - Crosman Powermaster 760. I got one in the late 60’s, and it STILL works great!
I second that , Crosman Pumpmaster 760 , $33 at WMT (I paid $28.88).. hits hard ,, sinks BB’s deep into my backstop (wood fence) at 100+ feet.
http://www.walmart.com/ip/Crosman-760-Pumpmaster-.177-Caliber-Air-Rifle/16536173