To make a correction. The Track hulls are lathe turned as well, and are thin walled to take the correct 9 gauge wads for antique Parker 10 gauge guns. If the Parker was made before approximately 1885, it's bore size will be larger than the modern 10 gauge standard of .775. They generally run somewhere around .790+, and will perform better with the larger 9 gauge wads if you are using black powder and card wads.
Obviously with brass hulls you must take proper care of them, such as washing and cleaning after use (a case tumbler is a big help). If you do that, they will last forever or a very long time, whichever comes first.
