Explain the argument between Mr. Tate and Atticus. What request does Mr. Tate make of Atticus?

From the text:

“Take him, Mr. Finch.” Mr. Tate handed the rifle to Atticus; Jem and I nearly fainted.

“Don’t waste time, Heck,” said Atticus. “Go on.”

“Mr. Finch, this is a one-shot job.”

Atticus shook his head vehemently: “Don’t just stand there, Heck! He won’t wait all day for you—”

“For God’s sake, Mr. Finch, look where he is! Miss and you’ll go straight into the

Radley house! I can’t shoot that well and you know it!”

“I haven’t shot a gun in thirty years—”

Mr. Tate almost threw the rifle at Atticus. “I’d feel mighty comfortable if you did now,”