On season 12 and I just thought of something...
How much shotgun ammo Hunters could save if they just brought in spray bottles or water guns filled with saline (salt water). I mean, definitely still bring the shotguns, but a spray bottle can be squirted across a room dozens of times. Also, same for holy water. I can't believe the writers for this show - seeing as how they love comedy - didn't arm Sam and Dean with little plastic water guns.