I use two main per charged air rifles, a air arms s510and a s200, both are very accurate the s510 is a .177 the s200 is a .22 .
My best results have been with the s510 a light gun easy to load, mine is fitted with a illuminated 3to9 scope.
Shots of around 50yards , head shots at 35 to 40 yards possible.
Good luck with whichever gun you chose.
Bert.