In fact, Jack Dudley had no time to think of anything except to run with all the vigor which nature had given him.
All at once he saw a spot where the feat looked possible.

There was no time for him to turn off to gain the momentum, but, measuring the interval with his eye, he gathered his muscles and leaped outward.

The jump was diagonal, and made under most difficult circumstances.
Who shall describe the awful thrill that shot through Jack Dudley when, at the moment of leaving the rocky edge of the rocky wall, he was sure he was about to fail in his last effort?
The other margin of the canyon wall appeared to recede, and he uttered a despairing cry, certain that the next instant he would go spinning down the frightful abyss.
It is at such critical times that the question of life and death is often decided by incidents so trifling that they are unnoticed.

Had Jack Dudley retained his Winchester in his grasp he would have been lost.

It would not have been alone the weight of the weapon, but its interference with the free use of his hands.