I'd recommend a Bushnell airgun scope, AO, I have one in 4x32, they make variables.
Have used a former Beeman SS2, a rare 3x airgun scope.
Also on springers used for ltd time, a 4x and more extensive, a 2.5x fixed. Both did ok for the time they were used.
Strong mounts are a must, springers will make weak ones slide...
Good bullets thru Vitals = a Proven Formula!
Game knows NOT - headstamps, MV, FE, KO, or Ballistic Gack.
Know YOUR rifle/load/sight in and hold/twist accordingly then S Q U E E Z E
6.5mm's - Dropping Lions, Moose, and Elephants since 1894.