Officers should always be ahead of the bad guy when it comes to protection so they should have superior firearms at work
While I agree the police should have appropriate arms I think since they are servants of the public they should be compelled to be highly proficient with the arms they bear. They should be shooting at least monthly and it should be a high enough number of sessions to meet some sort of standardized training requirement... Cant shoot then you don't get to be a possessor of whatever weapon as a public servant.
In my view states and counties should be liable if it can be reasonably shown that their officers are so un-proficient with weapons as to be a menace to the public due to inaccuracy. I wouldn't hold the individuals liable but rather those who should be funding the training.
Of course in my view military style weapons and military weapons (small arms) are all protected under the 2A and should not be the sole domain of law enforcement and the military and the handful of people with pre 86 weapons.