It's good that you are burping him often, as that's very important. You might even try to get a burp out before you start a feeding. And there's no one right way to burp a baby-do whatever works best for you.
Sometimes gas is relieved by changing the baby's position; for example, putting him on his tummy for awhile (not to sleep of course!). In fact, laying him on his tummy on something warm, such as a warm towel, will make him feel better. Also, you might offer even a few sips of water after a feeding, as sometimes that helps babies burp or pass the gas more readily. If the gas seems to be getting worse as time goes on, be sure to discuss it with your health care provider.