Hi I'm new to FT and I'm in the process of getting my old RWS model 45 .177 springer and a scope dialed in from 10 to 55 yards . What I'm having a hard time finding is the size of the openings that are used at the different distances . For example how far back can the smallest opening target be from the shooter .I found this on Wiki , the US, kill zone diameters vary from a minimum of 0.375 inches (9.525 mm), to a typical kill zone diameter at distance of 1-1/2 inches (3.81 cm). Occasionally, kill zones to the maximum allowed 2 inches (5.08 cm) are used.. But it doesn't say how far back the minimum 9.525mm opening can be set from the shooter .Is there a maximum distance for smaller opening ? Do the size openings have anything to do with the shooting positions ? How does this work for the US FT matches .