Maybe "killin power" was the wrong words to use as you can certainly increase the explosiveness on critters of less stature buy increasing speed and using bullets less hardy. But the same things that creates explosive results on a prairie dog can be a detriment for larger critters. Kinda like using lightly constucted varmint bullets in a centerfire is not a good idea for deer hunting. The same can be said when you use too solid of a bullet like FMJ's on game, again not a good idea.
But for it's case size, lighter/smaller/lesser construction doesn't = bigger critters.
