The G63 (G63C) is pretty easy to find because some of the groups attacking the military base have this on them, and it might be on one of the soldiers in the weapon storage. Although the MP7 might be a little trickier to find. Here is what the MP7 from Heckler and Koch looks like:
One solution is to hire the mercenary Fox, that has this weapon as default.
The cost to hire Fox is $24 720.
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