Suggesting a mod to reloading where reloading after only partially emptying a magazine throws away the rest of the ammo in the magazine (instead of magically teleporting it back into your imaginary total ammo pocket) would add to immersion/realism and make the reloading function much more tactical. Reloading every few seconds "just in case" would no longer be viable, and you'd have to consider the urgency of the reload vs. the tradeoff of losing the ammo that remains in the magazine.
Something like "New ammo count after reloading = old ammo count before reloading - mag size" (you fire either some or all ammo in the mag and throw the rest away when you reload).
Even better, having the magazine content be "Escape from Tarkov"-like where the ammo count shows as either "Full", "Almost Full", "About half", "Almost Empty" and "Empty" would be a bonus. But that may be asking too much.
I'd be glad to pay for something like this.