Ex-police officers should be able to keep their guns, those in the army should not automatically be allowed personal firearms due to philosophical reasons, being they are not the police and should not carry out those roles under the orders of the military.
Anyone with a criminal record is not allowed to possess a fire arm whatsoever.
I believe people should volunteer for police work and do work in the community. You know the sort of thing. Putting on a flourescant vest with community warden written on it and patrolling the high street on friday night and calming down drunkards. etc etc..
After a year or so then the local police will decide whether this person is eligible for a side arm.
If someone wants a hunting rifle or some other guns they have to possess a side arm for a year, with a L sticker stuck onto it. As if they are learning to drive a car, but in this case learning to act responsibly.
Ask any psychologist. Community service brings out the best in people and exposes them to emotions and human behaviour that they will see in themselves and learn to control. I believe in this way, allowing guns into the public must cause a lot less fatalities than disallowing them completely.