We may be limited to the semi-automatic version, but even without conversion to full auto, which actually has very little utility, we own pretty much any type of small arms, that any military owns. Also a few, not so small arms. We also own more of them, with larger stockpiles of ammunition, than all the worlds militaries combined.
Do we own modern fighter jets? No. Do we own modern missile systems? No. Are they required to win a war? No.
The only war we could not win with privately owned arms is a Nuclear War, but then, there is no such thing as a winner in one of those.