Never a truer word spoken Brian. I used to use old well thumbed oily copies on my workbench until I retired and left them for the other Armourers that hadn't even used Brens and Vickers guns. Re the Tool, adjusting foresights........
Kent, believe me........, you really don't need one. A total waste of space, time and effort and I never knew a real Armourer who ever used one. Just ask yourself this simple question. If we really did need to use one of these ill fitting tools (and the No4 and 5 ones were dire.....) why didn't we get one for the Bren or Vickers or Mk2 Sten or the No2 pistol or.................. And another thing...... How come they were any use given that they were so ill fitting over the protectors?
You just need to remember this simple formula. Foresight into the error. Backsight out of the error. Or if your shots are going left, move the foresight left!