I'm not actually certain when the two failed hits came out, so I'm taking a wild guess. If anyone can tell me where this one and the next one really fit in the proper order, I will renumber these later.

Story: CAPTAIN AMERICA#? by Mark Gruenwald (writer) and Paul Neary? (artist)
Synopsis: The Constrictor is in the hospital recovering from injuries in the previous issue. An overweight nurse pulls out a sawed-off shotgun. Before she can kill the Constrictor, though, Captain America intervenes. The nurse, actually Scourge, manages to escape.
Is it a key part of the Scourge storyline? Beyond being his first failed hit, no
Is it part of the main story in this issue? Partly since Constrictor is in the hospital for crossing the Serpent Society, whom Captain America has started investigating as a result
Comments: Despite the assassin's apparent weight, s/he seems to be wearing a padded suit, and thus is probably the same assassin as usual