What type of gun are you thinking about? I personally don't trust anything that requires batteries on a gun. With the possibility of low batteries, damage or other failure, I would rather invest my time in practicing with quality open sights. On my "emergency guns", I don't trust a scope unless it is backed by iron sights. I prefer open sights, whether on a rifle or handgun, since there is a lower chance of them being damaged. With practice, a good iron sighted big bore revolver can be very accurate at long range and reduced loads will work for small game.