Source: marvel.wikia.com

Chapter 3: Goliath

Hawkeye has always been the normal dude among the Avengers. He can't fly, he's not a genius, he gets hurt for real, and he can run out of ammo.

One of the classic Hawkeye stories that will play out again and again is the idea of his struggle against his limitations. The first big instance of this happened after his bow shattered during a pivotal battle and left him useless. Clint decided he was done being Hawkeye, and took up Hank Pym's former identity as Goliath, with what I will admit is a horrendous costume. Just a purely, deeply, bad costume.

Is he wearing the framework of a barrel on his chest?

During this time, his brother Barney also came back into the fold, allowing Clint to take care of some unresolved personal issues. He fell in love with the Scarlet Witch, and eventually left the team when she chose the Vision over him, retaking his Hawkeye identity.