I have a case I cut the foam for. Goddamn thing has never left the house. I will not make that mistake again. I would do this, or approximate it, if I needed a hard case.
http://m4carbine.net/showthread.php?t=33734
I cut my Storm case foam with a razor knife.
UPDATE: see new thread with review of choosen case here:
https://www.m4carbine.net/showthread.php?p=486998#post486998