The "Unload" trick.

[military30able]

One way to get ammunition from firearms that have leftover ammo is to pick them up and press the "Subtract [-]" key and whatever ammunition that was in the firearm will be put into the soldier's inventory. This can be done with any type of firearm: Submachine-guns, rifles, machine-guns, and even pistols.

I believe this works for the sequel Vietnam and the previous titles Red Tide and the original Men of War.

This might be done with stationary weapons, artillery, or vehicles.

[ShtoormoVick]

...Some real tricky trick, I must say.

[fak3d]

I think when i am really considering using this trick to get like 5 MG shots, the game is maybe already lost anyway

[manichero]

It had more use in the earlier games where the missions often meant that you were hunting for rounds hoping that you had killed a rifleman somewhere along the way just so your sniper could continue it rampage.

However on MOWAS im sure it could be useful for getting extra bazooka rounds instead of carrying the whole bazooka. Not the most important thing i know but could come in handy one day.