GMAW was used extensively when we built parts for the M1-A1. Tell your boss to get you a real welder. Unless your making those for Iraq.

All kidding aside, GMAW in (various transfer modes) is the way to go.

By the way, while in Saudi during the war, I had a chance to see first hand what happens when an armour piercing round hits a tank, amoured vehicle, etc. It's not a pretty sight. I was surprised how well the aluminum holds up to this kind of treatment despite the damage.

Anyway, get a GMAW for your weldments.