Brian, before you make the cut (which is not revesible) try this: Take a sharpie marker and mark the rail where the standards are after you focus. Do this for a while in as many situations of movement that you encounter. Then, if you are quite sure you will never need more extension, cut the rail so that all of your focusing situations are accomodated. Takes a while to collect the data, but it lessens the chance of going too short and coming up short on that once-in-a-lifetime shot.