Yikes. Those coins aren't the most accurate things out there. I used to use them till someone on here suggested feeler guages. Now that's all I use. I'd suggest grabbing a cheap set of feeler guages on Amazon or something.I was using a tool that look like a coin gaper to meassure it and gently with a hammer on tip to bring the gape down but to increase gape with the coin
Make sure to get a set that has .024-.030.
Much easier than guessing with the coin.