I've always wondered why the equivalent of aluminum heat sinks hasn't been tried with the "MG" type ARs. If you could pull heat away from the barrel [aluminum is good for this] and use the piston instead of DI to reduce return gas induced heating, then nickle boron the reciever internals, that might improve the auto rifle capabilites.
Heh, figure out a way to power it thermally and you could even add some small fans to help cool the barrel heat sinks [think PC processor heat sink/fan combination]
One of the few reasons I want a class three lower...so I can experiment with stuff like this.
"He who lives by the sword, gets shot by he who don't."
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