I fired a captured FN FAL. In Vietnam. I was told that the Australians carried the FAL. The weapon fell into the hands of the VC. I also know a little about the Swedish K. the French MAT 49, The USA grease gun, the British STEN. I fired all of them. In the 1970's the "Shotgun News" carried many ads for auto sears and blueprints on how to make them.