The insert barrels like 2-piper described are called Einstecklaufs, and are very useful, because the point of impact can be adjusted to correspond to what ever sights you have at any useful range. I use these in s couple of my drillings and have used them to take hare, squirrel, raccoon, and bobcat. The ones I have are in 22lr and 22 mag., but are available in many other calibers. The point of impact can't be adjusted with the chamber inserts, but they can still be somewhat useful at close range. The ones for shot shells shoot to the point of impact dictated by the barrel and can be very useful for various purposes.
Mike
