In a letter to his friend William Dean Howells recounting the heroic exploits of John T. Lewis, Mark Twain wrote the following in 1877:
Lewis, the prodigious … saw the frantic horse plunging down the hill toward him on a full gallop, throwing his heels as high as a man’s head at every jump. So Lewis turned his team diagonally across the road just at the “turn,” thus making a V with the fence. The running horse could not escape that, but must enter it. Then Lewis sprang to the ground and stood in this V. He gathered his vast strength, and with a perfect Creedmoor aim he seized the gray horse’s bit has he plunged by and fetched him up standing!
What is this "Creedmoor aim" he refers to? Is it a reference to the Creedmoor rifle range in Queens, New York?