It always bothers me when I empty my 1911 and the slide is still forward and not locked back. So I was hoping there was a way to make it do this when the mag is empty and your reloading, and/or when you are carrying no more of that kind of ammo. Is this possible or already done?

I'm not sure. It'd probably be possible with some creative scripting and animation tweaks.

I just figure "Eh, three hundred year old pistol, something is bound to not work on it" and go on with my combat.

AlexScorpion released a pistol reload animation that pulls the slide, but its life on the nexus was short. The effect is incorporated into the Book of Earache mod, but you'd have to go underground to find the animation in a stand alone package.

Will it effect any gun?

Any pistol that uses the 1 hand pistol weapon type and has a ##slide node, which is just about all of them. It does not back the slide when you deplete your ammo, nor does it keep the slide shut if you are reloading a partially emptied mag, but still works great for most of what you want.

So if I reload the slide like instantly goes back? That could make sense oddly. Cause then the mag will stay at 7 rounds and not get the +1 for the one in the chamber. It all works out ^_^ I wonder if someone could dice that out of that book of earache mod for me. You have it by chance?