You can't check the size of a thread with a pin gage. That would only validate minor diameter. The thread gage validates pitch diameter. That's mixing apples and oranges. The only thing you might infer with a pin gage is % thread (but only very loosely). Are all 20 features tapped with the same tool? If so, only check the last one machined.
What type of tap are you using (is it cutting or rolling the threads)? I would focus more on why are you making oversized threads than detecting them. We tap holes all day without being oversized.
They are actually studs we get from a supplier, and We have been having issues with them making the threads WAY oversized. We can have 1,000 good ones, Then one thats so large you can literally stick the bolt straight down into it without turning. So I just want a way to quickly verify. Not all the bad ones have been that oversized though, Most of the bad ones seem to be just slightly oversized, You can feel it when inserting the bolt, Its very loose and won't torque at all.
So how they are made or with the same tooling, I'm not sure of yet. Still waiting on info, Just trying to find a way to keep them from having to torque test every single hole.