here in MN, as a deputy sheriff, i have bought a new m4 (semi, 14.5 bbl, collapsible stock, etc) with personal funds. The caveat is that if and when i leave the service of law enforcement i return it to the county and they then reimburse me for the cost. if i leave the service of the county for a different agency, the weapon gets transferred to my new agency and i then possess it while there. as far as select fire, i cannot purchase with my personal funds, but through the dept, i can possess and use any type of weapon, be it short-barrelled, auto, semi, or whatever. that is not to be construed to mean that i can take a dept weapon to use for personal reasons, (ie personal range day, hunting) but i can take it to the range and blast away for dept practice/training.
edited to add:
and of course, all purchases made this way are on department letterhead and signed by my sheriff or chief deputy and that includes magazines.