Like others, it was my expereince (32years) that most state agencies Highway Patrol, State Patrol/Police will issue the weapon and ammo. If you are allowed to carry a 2nd weapon then you would have a choice based again on what the agency allowed.
After the S&W 9mm we switched to S&W 40cal. and I bought my issued 4013 tactical. A very sweet weapon.
My agency only bought American made cars and weapons, written into the state constitution.
Good luck in your pursuite of a life in law enforcment. No regretts on this end.