as for wet molding to a gun - before I'd soak it overnight I'd make sure it was chrome tanned leather to begin with.
Quality holster leather is veg tanned - and all that is needed to wet form veg tanned leather is a quick dip in warm water, some plastic wrap, a gun and very closely trimmed fingernails.
I'd actually be afraid to soak a veg tanned leather overnight for fear it would ruin it.
With my veg tanned holsters - I clean out the kitchen sink, fill it 1/2 way with luke warm water then submerge the holster completely. After about 30 seconds I take it out and set it aside to let it dry a little.
While that's happening, I wrap the gun in good, heavy plastic wrap making sure not to make it too lumpy - but covering it with two layers at least. Then, once the surface water has dried off the holster I jam the gun into it to where I want it to sit.
With your fingers, press the leather firmly to form it around the gun. I keep the mouth of the holster flared a bit around the cylinder on revolvers. If you pinch it there, the edge of the cylinder will catch when you put the gun back in. If you have fingernails - be careful or you will make little crescent marks in the wet leather that will be permanent.
If you want it formed to the point that you can just about read the serial numbers through the leather, then you're gonna have to go at it with some sort of tool - I use the polished, rounded end of a stainless steel butter knife..one of those colonial style "pistol grip" knives. You can also use the polished rounded tip of a deer antler...Press down around the gun and all over with the tool - pushing the leather to shape it around the gun.
Another way I do this is the put the whole thing in a food saver bag and vacuum pack it...works like a charm - especially for concealed weapon holsters - but you have to wrap the holster first in another food saver bag you've cut open and turned inside out - or else the ridges inside the bagg will leave marks all over your holster.
After you're satisfied with the results, you can pull the gun out and set the holster somewhere to let it dry overnight.
If you can keep your oven below 140°F and you want a rock hard holster, you can put a folded hand towel in there and lay the holster on top of it to dry for an hour or so. You want to protect it from the steel rack in the oven but other than that, oven drying makes a very firm holster shaped perfectly to the gun.