There are a lot of variables there, and unfortunately, there is no "one size fits all" answer.
- For example, hunting what?
- At what range?
- In which caliber?
You should also realize that while some makes and models of rifle
tend to prefer a certain pellet, they're not all the same. For example, my Benjamin Summit likes 14-16 gr. pellets best, but many others with this same powerplant say theirs prefers 18 gr. The accuracy difference can be significant, so it is really worth your while to test at least a few different pellets.
Being a Benjamin/Crosman product, you should at least buy a tin of Crosman Premier Hollow Points. They're cheap and usually locally available too. They're hard as rock though, so for smaller game, they'll over-penetrate and not expand. They blow right through squirrels with no expansion. (not good, since it doesn't transfer the energy you have on tap) You can lube them by putting them on an old, clean rag, give them a light spray of furniture polish like Pledge, and toss them around until they have a light coating. Let them dry, put them in a clean tin, and you're ready to go.