A quick check will prevent an easy to avoid incorrect measurement with any ball point gage.
Before inspecting, always verify the appropriate ball contact points. As you can do this when the points are on or off the gage, Gagemaker recommends checking points before setting up the gage or if you did not set up the gage just prior to use.
A quick check with a caliper or an OD mic will prevent this mistake. If unsure of the correct size of the ball point, the number portion of the model number will tell you the proper size of the point. For example, a T072 or S072 would have 0.072″ diameter.
It also helps to regularly inventory and organize your contact points. Having multiples of your most commonly used sizes means you always have the amount you need and you can set all of your gages at the same time without the hassle of swapping points between different inspections.