Can You Take A Ball To Use As A Gauge To See If A Ball Will Pass By Another Ball ? As In Checking To See If There Is Room Between The Rail And A Ball For The Object Ball To Pass.
3.42 DEVICES
Players are not allowed to use a ball, the triangle or any other width-measuring device to see if the cue ball or an object ball would travel through a gap, etc. Only the cue stick may be used as an aid to judge gaps or as an aid to aligning a shot., so long as the cue is held by the hand. To do so otherwise is a foul and unsportsmanlike conduct.