3D printing them directly using metal powder might get the look, but what happens upon the firing of a few cartridges?

Plan "B" is to 3D print a model from the appropriate "thread' and the use that as the pattern, suitably shelled and sprued, to INVESTMENT cast the almost finished item from actual steel. Don't forget to allow "scaling" of the pattern to compensate for shrinkage of the metal as it cools.

Ruger has been doing this since the early 1950's. They were the absolute pioneers in investment casting of Titanium and are still the world leaders in that field.

The basic technique has been around for over two thousand years.

Check your local business directory.