Feature request but this could be considered as a bug.
The respawn system allows to script for keeping all magazines in their state (load) when player die then respawn. (you can script something with EH killed/respawn and bis_fnc_inventory).
On the other hand, there is no way (no EH incapacitated/revived or equivalent) to manage the magazines loads for a player. Player haves always full mags when healed/respawned.