While silk would work since it is somewhat flame resistant material, where it would give himmore yards, I doubt it. A ball and patch is only as accurate as the load worked up. To simply pick a different kind of a patch seemed kind of strange to me. Besides that, silk is a much thinner patch material them most of the old pillow tick and muslin. So by decreasing the thickness of the patch they would have decreased the barrel pressure, which should have meant less power.

Considering when that movie time frame was, most of the rifles I would have thought would have been muskets. Notice there were no short starters in the movie, simply patch the ball and drive it down the barrel with the ramrod.That is a loose patch and ball combination. Seeing they were muskets, and no rifling, their over all range of accuracy again would have been effected.

I would write the thing off to movie magic.. but it might make for a fun experiment. Now where were them old silk shirts of mine...