How do "buy binds" / loadout macros work in Insurgency?

Other Source engine games like CS:GO allow players to bind keys to quickly apply a loadout, but I can’t get it working in Insurgency.

I’ve tried inventory_buy_weapon m16a4 and inventory_buy_weapon weapon_m16a4 (the slug defined in default_weapons.theater) in the console, but neither work. I’m I using the wrong syntax/values? I haven’t been able to find anything in my searches, but it seems like it should be possible, since the commands exist.