Gass relief hole botom of breech block.

[Vlim]

Luger frequently patented features on one gun type and then licensed his patents to be used on other types. Quite normally, as many features will work just as well on a rifle and a pistol.

Anyway, I think the flutes help in both situations: clearing muck and some gas relief.

The point remaining is that drilling holes in breech blocks of decent guns does not help their value.