Hi

I've found a amassing Free (CC BY 3.0) Impulse Response files pack for metal-guitarists (20 amps) here:
They are well trimmed and sound amassing, to be used with IR.lv2, jconvolver or guitarix.
 
http://www.virtualampstash.com/thread/191/ir-pack-metal-amps-bestplugins

Another Free Package from Dredd (Bestplugins) is here:
http://www.virtualampstash.com/thread/187/mega-ir-pack-bands-bestplugins

As well dedicated to the metal lover here. 8-)

greets
hermann