It is highly unlikely that any agency will entrust it's selective fire weapons to any reserve officer.
Actually I knew a guy who used that exact loophole.
He was a county reserve deputy and schmoozed the sheriff into ordering a Thompson M1A1 on the department letterhead at the LE price of $250.
He reimbursed the department the money and the sheriff issued the gun exclusively to him.
He was killed in a car wreck. I presume the Thompson is moldering away in a closet at the courthouse while the department has moved on to more modern long guns.
This was an isolated case and does not mean the OP and his buds could do something en masse. It was over 30 years ago before the 1986 repression and AWB, too.