Monty is correct. Armi San Marco is no longer in business (they were bought out and had their equipment turned to making cartridge guns). They made decent quality black powder guns which were generally considered to be less fine in terms of fit and finish than Uberti. They were also considered to have used 'soft' metal parts for several years.
My experience with ASM guns agrees with the fit and finish consensus opinion. I have not, however, personally run across an ASM gun with poorly hardened parts. I currently own one ASM gun, a Colt Walker manufactured in 1997. It suffers from a poor groove/chamber diameter problem, and the parts finishing (color case hardening, bluing and wood finish) is average but not poor. It is an average shooter in terms of accuracy, probably due to the groove/chamber issue.