Pops, your 500 should hold more than 3 shells -- the standard capacity is 6. If it holds only 3, the magazine tube probably still has the dowel in it that's meant to limit the capacity for hunting. Remove the barrel (see owner's manual), point the gun at the floor, and shake it a few times; I'll bet that dowel will drop out.
As to reloading... practice, practice, practice. It does make sense to learn do it with your weak hand. And you should practice, practice, practice shooting the thing anyway, so there's your chance...
