Not trying to sound holier than thou..but the old pie plate mentality isn't gonna cut it..I'd say a you better be cutting or very close to2" circle at those ranges. I wouldn't feel confortable with any less.

Things happen when hunting live quarry, you have to have confidence you can hit where your aiming. Because when emotions hit.. that 2" circle may become 4" which is much better than a 4" circle becoming 8"..etc