I have alot of trouble burping my 5 week old ...

I have alot of trouble burping my 5 week old baby after a feed. If he falls asleep while on the bottle or breast can i just put him in his cot without burping him or are you surpose to burp babies before settling them to bed. At night it is very frustrating especially when i am tired. I have been giving him gripe water at night so that we can both get some sleep. I try everything. I put him on my knee and massage his back, I try putting him over my shoulder or lay him on my tummy on his side and rub his back but alot of the time nothing works. Any ideas would be appreciated. Thanks Wendy