In Michigan you are required to register every pistol you own with the State Police after the sale. The required forms that are needed to register said pistols have specific fields that need to be filled out such as make, model, caliber, barrel length and number of rounds. With the capability of the SIG P250 to swap out calibers which will affect the round count and different barrel lengths and such how would this work out. The fire control system is the serial numbered part of the firearm which can be swapped into any number of configurations, and the serial number is with a very specific configuration is what is registered with the police. I was wondering if anyone from Michigan has had this question answered. If not I'm going to call the MSP and ask.