You haven't heard the negative part yet. The rifles were made by Voere in Germany. The ones made specifically to Klineguther's desires had a very soft receiver with a harded alloy bolt seat set inside the ring, and indexed with a set screw. The instantfire was just a marketing ploy the lock time wasn't any faster than a lot of other non mauser rifles. The ring around the bolt head was thin and subject to failure if a case seperated. The sear served as the bolt stop, and if the rifle was operated vigorously, eventually peened out of shape, with disasterous effect on the trigger pull. It had a good safety though that acted directly on the firing pin. When you come right down to it, there's usually a good reason these odd named rifles didn't catch on.