For sure the 416. Parts are a lot easier to obtain due to its inherent Armalite platform. And when I said Velocity Arms's HK416, its under the "custom line" link in AEG's. But honestly, that gun costs $350. If you decide to go with a metal body, chances are that'll run you up to $200. So...close to $600 total. For that you can get a retailer to get a full metal gun in for you. It might take a bit longer but its well worth it.
And no, AV'ing doesn't cost money. Just need a valid ID.
What's more important: morality or the freewill? In our society most people would say freewill. But we mustn't forget our morality.
Our morality guides our freewill to do the right thing.