I have a couple of Parker Hales made on the Mauser action. While bedding one into a new Boyds stock, I have discovered that the screws holding the action in the stock are not the right size/thread. What was in there is 1/4 inch 20TPI, and when i do the screws up, as they get further into the action, they bind up. M6 with a 1.0 thread pitch does the same, it just binds up quicker. 1/4 inch Whitworth don't work either. Does anyone know what is meant to be in there? Much appreciated.