This is a good suggestion, it also makes sense to keep the broken guns in case they need to be fixed by admins if needed.
I understand the issue though that was stated before that the broken guns would only be helpful to LEO's. Which in turn would make people loot again, since they want to get rid of the evidence. It would be less looting but it would probably still be an issue.
Maybe remove the guns completely and let people be able to post something like a refund request if they would realistically get a gun.
(+ harsher punishments, get rid of 30 minute ajails just give them a day off tbh, people can live without playing for a day)