At the moment we have removeAllWeapons which clears weapons and magazines from the units/players inventory.
It's more than likely a long shot, but it would be nice to have "removePrimaryMagazines" & "removeHandgunMagazines".
The idea of these commands are as follows.
init="removePrimaryMagazines this;" // <-- Will remove any magazine intended for a primary weapon, 6.5, 7.62 or 5.56.
init="removeHandgunMagazines this;" // <-- Will remove any magazine intended for a handgun or SMG weapon, 9mm, .45 and so on.
Both of these commands should clear out magazines regardless of whether the player has a primary weapon or not.
An example of this would be creating a trigger with
OnAct=removeWeapon "arifle_MXC_F"; removePrimaryMagazines this;