The object is to keep the duty match as even of a playing field as possible. It would be simple if every agency carried the same pistol and optic, but they don't. Some agencies have better equipment than others so we can't just say you must shoot only your duty weapon. The NRA rules spell out what is allowed. If it is a normal duty type pistol (NOT A SINGLE ACTION 1911) with a stock trigger, with or without an optic, then you should be good to go. You will need a holster that covers the trigger guard, 3 magazines and carriers, eye and ear protection.
NRA Rule 3.6
The League is going to adopt the (NRA rule 3.6 Stock Service Semi-Automatic Pistol) as the requirements for the duty match with the addition of 2 more prohibited items:
#11 No single action only Pistols
#12 No Compensators
Basic Overview:
NRA rule 3.14 (For all matches)
Basic Overview: Standard right or left handed holster that covers the trigger guard and has basic level retention.
North Carolina Police Combat Pistol League