My Glock 37 was an LE trade-in and therefore its round count could probably be determined by multiplying the number of years it was carried by the number of rounds in the department's qualification course. It sure looked like it hadn't been fired much.
Still, there's always the chance that it was carried by an officer who liked to shoot and, further, was from a small department without a department armorer to keep on top of preventive maintenance. Therefore, along with the upgrade parts in the box from Brownells, I also ordered some cheap insurance: