If you can, add a couple more pins to your sight. Then set up for 20, 30, 40, 50 and 60 yards. When I used sights, I' d mentally divide the space between the pins into 10 even increments. 42 yards would be two clicks under the 40 pin. 47 yards would be 7 clicks under the 40, or 3 clicks over the 50.