DO NOT use a saw-zaw! It will cause too much heat and the barrel will splinter. Now, you won't notice these little "cracks" but when you shoot it its gonna look like Elmer Fuds gun after Bugs stuck his finger in it.
If your gonna DIY put it in a pipe vice, mark it with a pipe cutter, use a new hack saw with a fine tooth blade to cut, and recrown it.
I've done this a few times, and if you do it correctly it will look almost factory made.