Typically, if an internal threaded part is cut too large (too much material removed during threading), it ends up being rejected or scrapped. Because API RSC threads are tapered, moving the shoulder back makes the “over-sized” thread essentially “smaller.”
When cutting/inspecting an internal API box rotary shouldered connection, it is not necessary to scrap the part if the thread is measured and found to be over-sized. If the stand-off is too large, the face of the box (torque shoulder) can be machined back by a corresponding amount (on the Z axis) to bring the stand-off back into tolerance.
For example, if the box was cut too large and the stand-off reads +0.003″, the face can be machined back a corresponding 0.003“. You can control this process by quantifying the stand-off using a Gagemaker ST-7002. In the example above, facing back the box 0.003″ brings the new stand-off to an acceptable 0″.