$F1::
{
  HeavyAttack:=!HeavyAttack

  if (HeavyAttack)
  {
    SetTimer, HeavyAttack, 350
  } else {
    SetTimer, HeavyAttack, Delete
  }
}
return

HeavyAttack:
  Send {LButton Down}
  SetTimer, HeavyAttack, Off
  Sleep, 1700
  Send {LButton Up}
  SetTimer, HeavyAttack On
return