Home Forums Hunting & Shooting Ask The Gunwriters Metallurgy, Ruger Investment Casting, Action Strength?

The point of casting is to have an efficient way of making complex shapes, that are either impossible or cost prohibitive to forge. And forging dies - hard tooling - take a lot of abuse and tend to be relatively expensive. Casting patterns can generally be relatively low-strength, inexpensive materials.

Good castings will be clean and dense - not a lot of impurities in the metal, nor voids (air bubbles) that formed when the metal was liquid. Impurities can act as stress raisers, and cause premature failure of the part. Voids are an obvious problem.

Firearms receivers are generally designed to have good strength, but also good toughness, not brittle. A brittle part could shatter with an unexpected stress, like an overload, and be very dangerous to the shooter.

Good forgings will usually have better ultimate strength and toughness, but a Mauser-style receiver was designed in the days of weaker steels; a good casting is plenty strong enough. In higher-stressed, really critical parts, like barrels, you will still see forgings, and bar stock production.

Aside from clean, void-free metal, a good steel casting will then depend on a good heat treatment. In that operation the grain size and strength/hardness can all be refined to give the desired properties.