Georg Luger adapted his famously successful toggle lock form the Luger automatic pistol into a self-loading rifle for the German military. It was built in 8mm Mauser, but only a few prototypes were ever built.

Luger 1906 semiauto rifle in 8x57mm
Luger 1906 semiauto rifle in 8x57mm

According to the related patent (which you can download below, thanks to a fellow name JonMac who found if for a post on The Firearms Blog) the rifle incorporates an improvement over the Luger pistol mechanism. The pistol was known for having minimal spring pressure holding the toggle closed – a little dirt in the chamber or a bumping the cocking knobs upward could inadvertently keep the action from going fully into battery. This rifle design uses a different setup to put more positive spring pressure on the toggle when closed. This would probably not have been very easy to retrofit into the Luger pistol, simply because of space constraints.

Luger semiauto rifle toggle lock improvement
The rifle recoil spring would be the primary force on the toggle when the action was fully open. As the toggle closed, the leverage of this second spring would increase, solving one of the main faults in the Luger pistol.

Patents

UK Patent 4126 (Georg Luger, “Improvements in Recoil Operated Fire Arms”, July 26, 1906)

Photos