Board Thread:Questions and Answers/@comment-7823447-20140421150120/@comment-4651179-20191215000849

Captain America's shield offers a limited range of protection since it's literally just an oversized dish, so it can't block all kinds of attacks. On the other hand, Iron Man's armor covers the entirety of his body, and on top of that he can create energy shields. Iron Man's armor also has magnetism, which is worth taking into account since Captain America's shield has sometimes been portrayed as magnetic. Even then, Iron Man could disarm Captain America through other means. Since the shield is also a weapon, all it takes is for Captain America to toss it for Iron Man to deflect it with a repulsor ray, given the reaction time of his armor. Captain America's shield also only protects him against targeted attacks. Iron Man's armor can deploy sonic attacks not unlike those he used against Captain America in, multi-vectorial repulsor rays like he used in or multi-directional micro missles that Captain America can't protect himself against if they hit him simultaneously from different sides.

As for grenade launchers? Iron Man's armor can protect him against nuclear explosions, as shown in.

And again, I think it's silly to bring up a story-specific item like Mjolnir. But if you would like to, it's not like Tony doesn't have his own Thorbuster Armor which can repel the hammer. Can you really claim that Captain America can defeat Iron Man if you have to resort to such specific battle parameters?