if you use the 16oz style boxing gloves on your bag you might end up hurting your hand in a real fight. i say train with the gloves you are going to fight with. no one really knows how hard a guys head is actually going to be until you hit it. this way it toughens up your hands and wrists. if your hands hurt afterward, good, get used to it for your fights
WHAT??? That is some of the WORST advice I've ever seen, If you are hurting your hands hitting a bag, you're not hitting the bag right....
if anything using MMA style fight gloves on a heavy bag you are more likely going to kill your wrists then hurting your hand in a fight, and you usually don't need to have your own fight gloves MOST promotions will supply you with a pair.