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Finally there is an alternative to the home builder to make your own professional grade 1.5mm receiver from a flat. The material these are made from is .063 4130 Chromoly steel that is in the annealed condition. Yes annealed means it needs to be heat treated. Yes the flats come with rails as always and both are made from annealed 4130 and are .050" thick. The mag stabilizers/guides need to be trimmed just like all of my other rails.
These flats do NOT have any trunnion, center support, trigger guard, axis pin, sling swivel slot or selector holes drilled.