When I worked in a forestry job in Upper Michigan in the late 90's, I had the opportunity to talk with a large number of retired LE and prison guards who ran the local shooting club as state max security incarceration was a local industry. As far as I could gather, any rifle used in duty other than some surplus M17s, Springfields and Krags was either brought from home or was a rifle confiscated during operations that was commandeered by the local LE jurisdiction for duty use up until sometime after the Korean war. At that point, they tended to drift towards surplus M1 Garand or Carbine rifles procured from the Natl Guard armory, although some deer rifles were still kept in inventory even during the time I was there for wildlife work, although they were all bolt action .308 or .30-06 at that time and likely seized by Fish and Game. The M1 and M14 surplus were also inventoried, the M1 carbine had just gone out of service. Nobody talked about any accessorizing other than perhaps a bandoleer or shell wallet. They did have some special ammunition though. It was still inventoried when I did my LE range qualification for wildlife work, and was in the process of being phased out of service so was available to check out for range duty as well as the rifles to fire it. There was an enhanced penetration load available for .30-30 and .300 Savage. Winchester LE marked (1950?s) with a sort of flat pointed FMJ looking bullet. The .30-30 rifle was a well worn generic Marlin...sears or stevens or some other jobber with no modifications and lots of wear from patrol car hangers. The savage (I saw the picture) was an early M99 and "on loan to a superior" at the time I did qual. The .30 cal military surplus rifles had military AP inventoried, and I got to rock and roll some with an M14.
The local shooting club had a picture on the wall of several guards, some were present at the club, guarding a POW camp during WWII (apparently there were several in the area), and all of the guards had either a sporting lever or a Krag, and one very menacing individual in a buffalo plaid Mackinaw with an M97 and short barrel. They said they had the choice of a Krag from the State's armory or a personal rifle, and most just brought their deer gun. Saw no evidence of mods, but most had a sling of sorts. One guy had a big Pancho Villa style bandolier slung over the shoulder, likely posed for the photo.