Handguards and barrel heat.

[stupidfast]

I have a 16 in BCM upper with M4 handguards. I was wondering if the M4 guards are bad for keeping heat in. Would a rail system be better for heat loss or would it even be a noticeable difference? I can count on one hand how many 30 round dumps I have done, with a long cool down period afterwards.
All I want on my rifle is a bipod so there is no need for a rail other than heat issues. Thanks for the help.
P.S. As soon as I can find a way to hide it from my wife I want to get a 10.5 bad! Maybe a rail system on that one.

[markm]

Standard handguards are fine.

If heat is what you're concerned with, pick up a set of Colt oval/double shielded handguards over on the ARFcom equipment exchange.

[lindertw]

I ran a temp test on a barrel mounted light a while back. Post #9 in this thread (http://m4carbine.net/showthread.php?t=16681) may be of interest to you...