Headlight bulb replacement on an '04 stratus w/a stuck locking cap

Grr I am looking for any who may know how get off a very stuck locking cap (black piece of plastic that screws on to hold bulb in). I tried for a couple hours last night to get it off but had no luck. I also had a couple guys I know try to get it off too,they had no luck either. Is there a special tool or anything that may make this easier because right now I would like to beat it senseless. I don't really want to have to pop out the whole headlight ass. Txs.