Realistically, anything under 2-inches at 50 metres with open express sights is a good shooter. Some will do 1 1/2-inches or less, but probably not many. With a high-quality scope fitted, you should be able to cut that group size in half.

A big-bore double which only shoots 3-inches at 50 metres probably shouldn't be chucked away, though!

Three pairs of shots off the bench, BTW.

Double it, plus 10%, for 100 metres.

Just MHO.....