Is the sintering strong enough for the chamber and barrel to work multiple times? That seems more a prop/model than a real thing.
Bronze was used for cannons for centuries. I wouldn’t trust it for hot or magnum loads. It’s more for acquiring a hostile’s arms by surprise.
For a more than mouse gun load, one might make a wire gun. 1890s technology when the steel and forgings of the day weren’t quite up to the job...
Stratasys makes rocket engines and gas turbine blades with DMLS, for whatever that’s worth.
Robert Hofmann GmbH has utilized 3D printing technology to create a fully functional cylinder block for a Volkswagen engine.
The pounding of 4-cycle combustion is probably pretty close to the pressure excursions of rounds being fired...
So yes and no.
There are models for low pressure loads. There are also models that allow you to insert a metal tube of the proper size and allow you to create a barrel that is more durable, maybe handle more pressure.
Most 3d printed ghost guns are the AR15 lower receiver. Since that does not actually handle much in the form of pressure, it does not need to be all that strong.
Finally, there are models that can be printed in plastic / wax and used to create a cast barrel. This is a somewhat risky proposition as weak points can be created in the barrel. Some creative and daring folks are working on how to make a barrel but that is too risky for me. I just buy barrels because I like my face and fingers just the way they are.