A couple years ago, I loaded some .45 ACP using an old can of Herco that my dad had from his 12 gauge reloading (he used to load for skeet).  The powder was around 15 years old, but he kept the can stored properly, and it smelled ok, so I used it.  Cartridges went bang just like they should have.  Older powder that was properly stored can still be ok, but make sure you check it!  By the way, I still have that can of Herco!