It seems most new 1911 type pistols come with flat main spring housings. I've always preferred the arched. I've had this 1991 Commander in the safe since I bought it new around 1996 and had the late Joe Bonar of Novak's install lo-mounts and do a trigger job. While I was at a gun show in Dulles, VA picked up a arched MSH and a spur hammer, strut, and pin from a gentleman who had bins of old stock parts for all things USGI. I've always liked spur hammers more than rowel-type for the 1911. Anybody else prefer arched housings? Before and after pics below.