Rare German WWII 10.5cm Cannon Bore Sighting Tool

This is quite an unusual and rarely if ever seen item of German WWII military field equipment.
The flat brass disc with the two large holes and central pin hole would be placed in the barrel breech the two large holes to are for your fingers to locate the disc, the disc would basically act as the base of a 10.5cm. shell.
The other piece with the cross hairs would be positioned into the muzzle the rimmed edge would prevent it from slipping into the barrel.
Once these two parts are positioned the gun crew could simply test the gun sights by directing the barrel at a set object in the distance look through the pinhole of the chamber breech disc and align with the muzzle cross hairs onto the set point and then check that the gun sight is aimed onto to the same spot, if not adjust the sights util they correspond.
A simple battlefield method of quickly checking sights.
With cleae acceptance marks on both items WaA107

Code: 50859