Actually it can be a problem, temperature changes can create moisture inside the gun. BP and BP substitutes are orthoscopic, meaning they soak up moisture, causeing ignition failure. Its happened to me in the past, which is one of the reasons I bought a Savage(smokeless). You will more than likey be OK if your shooting an inline 209 w/ BH209 or 777 but BP and pyrodex is very sensitive to moisture and#11caps might not be hot enough ,if powder was exposed to moisture at all. If you dont want to take a chance, you might want to fire it at the end of the day and load it fresh every morning, to me its a little extra effort well spent. If not ,you might want to at least aviod drastic temp. changes like bringing it inside or in your car w/ the heat on.