They can be used to reach far-away areas (both vertically and horizontally), break through weak blocks, and kill Enemigos (being a one-hit K.O.). Oddly, they appear to make Cactus McCoy immune to hazards such as fire and Crushers while riding them. It appears that Barrels Rockets that travel upwards have orange wings, and those that travel to the sides have red wings.An alternate version, called Heat Seeker Rockets, appear in Cactus McCoy 2 only and cannot be directly used by Cactus McCoy. They are distinctly completely red-colored (as opposed to the regular's complete brown), and seem to spawn in an unlimited supply.
They actively follow Cactus McCoy, as their name suggests, and will harm him if they hit. They can be used indirectly, however, such as if McCoy lures it to weak blocks blocking a path and jumps. If timed right, it will collide with the weak blocks while turning upwards towards McCoy, destroying them like a regular Barrel Rocket would and allowing McCoy to get by. This also works with Enemigos.