Well I know nothing about guns or 3-D printers but I need to ask this.
On a recent CSI TV show, they figured out an assassin was using a gun made from a 3-D printer.
The scenario was that, yes it was destroyed by the single shot, but you also had a bullet with no lands and grooves.
If he needed to do another hit, he just printed another gun.
Is this possible or just TV hokum?
Yes and no. Like the original article, the screenplay is confusing 3D factors with things that are there for functional reasons. The rifling isn’t a side effect of the manufacturing process, the makers go to a lot of effort to put it there. So, yes you could make a smoothbore printed 3D, but so could you using old tech, and you could print a rifled barrel (given a satisfactory printer/feedstock) just as with conventional tech. IOW, a smoorebore/zipgun made with old tech would have the same advantages and disadvantages vs a rifled design as a 3D printed smoothbore would vs a printed rifled design. In fact, you could even argue that as much of a pain as rifling is, it might even be EASIER to print it, so there would be LESS incentive to print a smoothbore.