I’ve updated my earlier heat dissipation graphs with the KAC M4 RAS. This is the railed handguard used by the US military on Colt M4 carbines and similar weapons. I did not have rail covers on the handguard during this test, because I was also comparing it to some other railed handguards.
Here are the handguard temps:
And the barrel/gas block temps:
Not only did the M4 RAS transmit less heat to the shooter’s non-firing hand, it also allowed the barrel to cool faster than the plastic handguards. This is in addition to its other benefits, such as mounting various accessories.