Try, Hot- Power, they have 20c 11.1V LIpos, i think not too sure, you should stick with 15C anything over 20C is usually for RC-racing you can go up to 30C, but they screw ur gun up big time ,
but just like m102404 id suggest king arms lipos, they are awesome, worked the best for me, i think they are the best lipos for airsoft. i run high speed set ups and they work wonders with ROF