I posted this in the r/insurgency reddit to a lot of good reception. It would be a good roleplay feature when mod support comes along (See Trouble in Terrorist Town, and like custom games), but also it could add to the weight vs movement speed mechanic. Out of ammo for your primary? Throw your gun away to get a little extra speed! Need to go defend an objective, and you're at spawn? Throw your gun and grenades to get a boost. and so on. In my mind it would be faster to throw your primary and draw your sidearm than to just switch between the two, but I'll let someone without a film degree figure out balancing.
I would love a drop weapon key bind