Strange tap inside Garand receiver - help

[ROCK]

This was also posted on Jouster and there was an answer:

I found a German laser proofmark on the barrel - so I contacted a German gunsmith which is specialized in historic firearms.

He told me the answer instantly.

The modifications are only caused due to the former KWKG (law) regulations in Germany. Before 2003, all military selfloading rifles owned by civilians had to be prepared, so that an original receiver and bolt (or bolthead) would not work in a civilian rifle. By doing this stunt the reciever or bolt would not work in military rifles - and a military bolt would not work in a civilian owned rifle.

http://www.jouster.com/forums/showth...ver-help/page2