so idk if this was already known or not, but basically you can weapon swap during the animation of aiming to quickshot, and it uses the ammo of the weapon you aim with. in this case swapping the crowbar to the shotgun lets me fire into negative ammo essentially having unlimited shotgun ammo. however its borderline impossible to do the double damage glitch with this for some reason (it is possible tho.) but yeah i dont think this is actually useful anywhere but it exists.

Neat. At long range I couldn't get this and the double damage glitch to work. Tried probably 100 times with various timings on reopening the inventory. However, you can do the double damage glitch at close range(crowbar range) and it happens automatically when you switch from the crowbar to the shotgun and shoot. Thanks for sharing :)