Chris, when you measure pocket with a tape like you are showing, that's not a true measure mentioned of the pocket because you're measuring the points of the corner pocket that the balls don't come into contact with as they touch the pocket facings well below those measured points, in which because of the down angle, are in fact wider than the points you measured. For the most part, the pockets depending on the down angle, are any where from 1/16th to 1/8th wider at the ball contact point than the measurement from point to point across the pocket opening. When you place the 2 balls across the mouth of the pocket side by side, that's when you get the true measurement of the pocket openings. If the balls sit half way between the points of the pockets, that's 4 1/2". If one ball is lined up with the points and the second ball sits outside of that center line, you can then take a look at the eclipse of the 2 balls and subtract the eclipse from 4 1/2" to get a better idea of the pocket opening.
