Clearning up the confusion about Keltec RDB and M43 action type.

From Keltec designer: “The original prototype was a long stroke piston (Like the SU-16), which is probably why the leaked ad said so, and why there is some confusion. But the current production RDB is a short-stroke piston operation, similar to the RFB. The piston only moves about an inch before it stops, and the bolt continues on to cycle the action.”