The first release used an updated version of the Notlob's Bolt Thrower (shown below), as did the Dwarf Bolt Thrower. Whether this was coded C22 or C27 is a question. It's also possible that the later version was never released under the C range, being maybe too late for that.
Like the Dwarf Gyrocopter, this may or may not have ever been released in the C22 range.
