MIM is indeed a major cost savings.
While molds and injection systems are expensive, one must consider the cost of dies and presses used in forging. The MIM tooling may have a greatly increased tool and equipment life.
Outside of that, the MIM parts require much less machining to bring them to a finished product. Many details can be cast directly into the part, like serations, texture, clearances, etc. All in all, only contact and functional surfaces really need to be precisely machined. I am not sure about the heat treatment after machining.
Contrast this with a forging. The rough shape may be there, but there is a large amount of material to be removed. Any surface textures needs to be milled. Heat treatment must be done carefully so as to avoid warpage of the part.
The forgings may be stronger, but strength beyond what is necessary to function properly and reliably translates into excessive cost. If a hammer or other component requires a certain tensile strength, yield strength, and hardness to reliably last 100,000 rounds, then increasing the strength, hardness, or both may improve the life of the product in theory, but the practical effect is minimal. Most handguns will never see enough rounds to experience failure. Some will, but most will not.
This is the same reason why Craftsmen tools are no longer made out of spendy vanadium steel. The steel material used to be better, but for 99% of users, the material properties far exceeded the needs of the user. The excess cost made the product less competitive.
While molds and injection systems are expensive, one must consider the cost of dies and presses used in forging. The MIM tooling may have a greatly increased tool and equipment life.
Outside of that, the MIM parts require much less machining to bring them to a finished product. Many details can be cast directly into the part, like serations, texture, clearances, etc. All in all, only contact and functional surfaces really need to be precisely machined. I am not sure about the heat treatment after machining.
Contrast this with a forging. The rough shape may be there, but there is a large amount of material to be removed. Any surface textures needs to be milled. Heat treatment must be done carefully so as to avoid warpage of the part.
The forgings may be stronger, but strength beyond what is necessary to function properly and reliably translates into excessive cost. If a hammer or other component requires a certain tensile strength, yield strength, and hardness to reliably last 100,000 rounds, then increasing the strength, hardness, or both may improve the life of the product in theory, but the practical effect is minimal. Most handguns will never see enough rounds to experience failure. Some will, but most will not.
This is the same reason why Craftsmen tools are no longer made out of spendy vanadium steel. The steel material used to be better, but for 99% of users, the material properties far exceeded the needs of the user. The excess cost made the product less competitive.