moa - i hate to ask but

[Rocky Raab]

I'll just jump in here, becasue scooter's next thought will be, "How do find the center of a hole?"

The two easiest ways to measure a "center-to-center" group are:

1. For groups where the widest holes are not touching, simply measure from the inside edge of one hole to the outside edge of its opposite hole. That's exactly the same as measuring from center to center, you have simply displaced the calipers a half a hole. Or,

2. Where all the holes touch (making one of those beautiful "wallet" groups), you measure from one outside edge to the other outside edge and then subract the width of one caliber. That's the same as moving in one-half a hole from each side, again giving an accurate center-to-center measurement.