yeah someone got lazy on the coding, in ro/dh there are separate reloading animations, for non-empty mags, and for empty mags, the latter including the slide/bolt in open position, and release of slide/bolt, whereas the former animation doesnt have a bolt/slide cock, because there is a round chambered.
(you can ignore this)----also, just to correct a little bit, most gun's bolts/slide dont latch on the mag's follower, the follower just lifts a catch that holds the slide/bolt open.
there are some guns that DO rely on the mag's follower to hold open the bolt/slide, but if the mag is removed then the bolt/slide releases into the forward position. i think the yugo m70 or some romak variants do this, which irks me because that is not a good design.
so we just need to toss in a little bit more code to say "hey if the guns not empty, play this reload, but if it is empty, then play this one, and adjust the ammo count necessarily (15+1 chambered, etc)."
i think sorrow's usp40 has this, but i cant remember.
another thing you can simply do in code, without having to reanimate, is to say "collapse these vertices to this bone" or something similar, like how the bloat gets "halved" or you can say "apply this rgb to this pawn's texture" or "attach smoke emitter to this pawn when burned up" there's lots of things that can be done easily, its just nobody has bothered to do it (we all have our projects). plus the emitter stuff might be too much for some ppl's computers/laptops.