Picking up LMG results in 1 round "chambered" and an extra mag

When I pick up a PKM or M249, it quickly does a little animation glitch and the magazine is moved off the weapon and into inventory. It still looks like a loaded gun, but it fires one round and then I have to reload.

First off, the mag bug needs to be addressed, but also these weapons fire from an open bolt, so there is never one in the "chamber" as with other small arms.

Also, tapping F on ammo box before reloading prevents me from getting more ammo. So I am forced to reload, then tap F, to get a proper loadout.