The bottom photo of this pair shows how the long military stock was shortened. The lightening cut in the forearm was filled with a piece of walnut.

The top photo in this pair shows the trip pin. This was set into the left side of the receiver rail, with a corresponding small hole in the outside of the left side of the receiver. The trip pin causes the extractor to release the auxiliary extractor. The auxiliary extractor then snaps back into place, leaving the fired case on the loading tray or just barely in the chamber. There is no ejection. The shooter has to use a finger to flick the empty out of the way and into the void below the loading tray.

These Krag actions were the last ever made. SNs are higher than 475,000. I am not sure that they were case hardened in the same manner as the purpose-made military rifles. The bolt works with a herky-jerky movement, not at all the slick motion we expect from a Krag. Much of that is because pulling the bolt back compresses 2 small coil springs that are part of the auxiliary extractor. The trip pin adds to the bolt's tendency to bind.

The original magazine & follower were retained in the full military GPR. With the magazine in place, the left side plate was commonly removed to allow empty cases to escape from the rifle.