It is the AK47 assault rifle, the preferred weapon of your enemy, and it makes a very distinctive sound when fired at you. For those recent to this subject, yes, it is completely legal to build your own weapon for personal use, as long as you comply with all laws on specifications and operation.
(Hey, Eric Holder: FUCK YOU!)
Reparkerized this (my riot gun, MI police surplus and very well used and worn)($130 shotgun with $1000 of accesories)
and this (1888 Commission Rifle, which I got as $25 worth of busted parts and have rebuilt since)
I also prepped two more demilled ROMAKs for next time, and parkerized two other barrels with help from fellow author David Burkhead doing much of the blasting and dipping for me, and making sure I didn't lose track of time while doing other things.