John,
Although it can't be determined for certain because of the slight angle of the photo rather than straight on, it does appear that the gun is a locked breech standard toggle configuration that must be manually operated. The forward toggle link to breech block pivot point appears to lie above the line of the rear toggle link pivots. Since the receiver is fixed, there is no "breaking" of the toggle knobs on the receiver ramps during recoil to unlock the action.
