Yes, firing pin was probably removed, no ammo with it, but a box of 500 30-06 rounds is like 40$ at cabelas. And the firing pin is a pretty easy problem to get around. The real problem would be someone taking it and geting it to fire, and THEN going and roving a bank. A security guard won't get in the way of a guy with an mg.
I can see it now, "skippy" walking into the Bank of America branch brandishing a .30 cal browning MG. Oh, come on. Bank robbery is best done with a small, concealable pistol, or JUST PUT YOUR HAND IN YOUR POCKET and claim to have one. When is the last time you saw a guard in a bank, anyway? I don't remember the last time. Except on TV. That's because all banks have a policy of giving a robber anything he wants, no discussion, no argument. It's only money, and it's insured.
Full auto weapons are legal, nemisis. There are almost 100,000 fully transferrable full auto weapons out there in the USA right now--and none of them are being used to rob a bank or liquor store. If some "playa" is using one for that purpose, it is no doubt (easily) converted from a perfectly legal semi-auto weapon.