There's a lot of apples & oranges on this thread... Here are some generalities for when comparing similar quality cast and forged parts. That includes similar alloys and proper heat treatment. Forged parts are going to be springier (more resilient) than cast parts. Therefore, things like hammers and firing pins that take a lot of impact type wear are NOT good parts to make from castings. Neither are things that are expected to flex during normal operation. Cast parts CAN be harder depending on the heat treat and alloy. So, it's possible to have a "stronger" (harder) cast receiver than a comparably sized forged receiver. But... Cast parts tend to fail spectacularly when they break. That's because they don't have a lot of grain and when they break, they tend to go into lots of pieces. Forged parts stretch and split when they fail, but their grain structure tends to keep them from shattering.