Haganah - TMT IV Sten markings

[Flying10uk]

I take it that by "galling" you mean deep scratches/grooves? On the edges of the die blocks it is normal practice in toolmaking to radius these corners off so that as the metal is pushed down into the die it flows over the edge without digging in too much. With the Lines Brothers cover these rads either require increasing slightly or, through use, the tool edge has "fired up". This is where tiny amounts of the metal being worked has transferred itself to the tooling causing a rough surface to build up on the tool which in turn then scratches/marks the metal being worked. Normally this can be removed and the surface cleaned up by the use of an oil stone and emery cloth but not with power tools. It is normally advantageous to use an oil or thick cutting liquid as a lubricant when working with form tools in order to help the metal slide over the tool without binding.