The squared-off breech face is a relatively uncommon alteration but is eminently feasible and actually IMO can be A LOT safer than a cone breech done by an amateur or careless workman. There are several areas that invite a mistake by the unwary, specifically the measurement of the cone depth and the cutting of the extractor notch. The flat face is also a lot less work and IMO makes the action somewhat safer as well if gas release occurs, due to the right-angle turns as opposed to the angled ones of the cone.
Regards, Joe

You can lead a man to logic but you can't make him think. NRA Life since 1976. God bless America!