[sholling]

Metal Injection Mold is correct. Molten metal is injected into a mold to form complex shapes inexpensively. Before I switched to computers I spent 20 years as a tool maker (glorified machinist) and I know a lot about the subject. With the right metal formulations, and correct conditions and proper quality control MIM is fine for moderately stressed components. Blasphemy I know, but MIM is fine for most moderately stressed parts if it's done right. The problem is that if the wrong material is used, or if the process isn't done correctly, or if proper quality control isn't done then you can get a brittle product. Lot's of ifs.

Parts machined from solid bar stock, if properly heat treated, are usually much stronger. The problem is that the cost of machining for example a thumb safety out of sold bar stock - even with modern CNC equipment is impractically high. Many times the cost of injection molding.

The next step up is metal forging. This is similar to stamping but involves much, much heavier material and high tempertures. Out of the three methods, assuming that high quality steel is used, and proper quality control is maintained forging can produce the strongest components.

Is it worth the added cost? That's a big maybe. For slides and frames I'll always choose forged steel, but machined from solid stock is in reality plenty strong. Barrels can only be machined or forged and then machined. It's pretty hard to justify machining a thumb safety from solid bar stock. It would also be a complex part to forge but it could be done for a premium price. In reality a properly formed and heat treated injection molded part would probably last a lifetime. Then again a flaky process or flaky materials and flaky quality control may let a few excessively brittle pieces out into the wild. I like to keep MIM parts to a minimum but I'm realistic enough to know that I probably can't afford a 100% forged components handgun.