Only carrying one stack of ammo for the sidearm, and having it ‘attached’ to the sidearm makes the first time one pulls up the said sidearm cause a reload. If one more box of pistol-ammo are carried, it works as it used to ((golden) Möller and Klaucke effected by it at least)
As when switching between weapons, the ‘ammo-unit’/stack tied to the weapons suddenly disappears into limbo if looking at the counter while switching, only to be remembered again when switching back. It might be the same kind of ’ counting problem’ that causes sidearms to not know they have a full ammo-stack attached already and going into reload animation?
Had this happen too, though only the first time I switch to my sidearm after loading in. I actually have seen the same issue intermittently with other weapons as well if they weren’t in the first weapon slot (and thus didn’t start out in your hands when you load in).
I did a little repro of how ammo is counted/loaded when only having one stack.
Just swap place of the 2 main weapons while using the sidearm (that initially reloads when pulled up) and they both reload when swapped to. It can be recreated by changing place of them again.
(The famous AK4 (HK)-‘Slap’ isn’t included in the animation, but as long as misfire isn’t in the game it would just be overkill to have it added, even as it’s almost the AK4’s trademark™) 