What is the best way to store an unstrung bow?  Vertically standing on end, vertically hanging on peg through string keeper , or horizontally on rack?  Or does in really not make a difference?

Not standing on its end thats for sure the other two are how I store mine.

What Mr. Jones said.... Never store a bow standing on its end. This should be reserved for short periods of time in the woods and maybe at/while shooting.

i always hang mine from the string unstung