Varmint for score is open for light, and heavy varmint rifles as well as hunter class. You need to check the rules at the range you will be shooting at. If they are shooting varmint for score in light or heavy gun class scope power is unlimited. Now if they are shooting Hunter class there is a few other rules that go along with that class, One the stock has to be no wider than 2 1/2 inches, it must have a mag well cut in the bottom of the receiver, (You can still use a single shot adapter but it must not be attached to the receiver.) besides the 6 power scope there is limitations on cartridge size. Hunter class is shrinking in participation, and many clubs are getting away from this class. Some clubs have a "factory" class , and they usually do not limit scope power. Checl with the match director , and see if they are shooting Hunter class, and what rules they have.