Being able to do tactical reloads / speed reloading.
Dropping the old or the new magazine on the ground to reload faster.

*Magazine remains on ground until picked up or garbage collected.

The mechanic could be something like:
R → Normal reload
2xR → Tactical reload and keeping the same weapon.
*While reloading:
2 → Changes to secondary weapon
G → Throws a grenade (smoke / frag)

• or any other actions that would normally be blocked by the reloading animation.

This would be a really nice feature to have. It will bring the game closer to reality as relieving some frustration caused by getting attacked while starting to reload or just because we press the wrong key.