While this is true for 100% printed guns, most fosscad folks will have core components that are metal. Barrels, firing pins, etc will be metal in most designs.
Some folks claim their guns can shoot thousands of rounds with no issue.
> They will have very poor accuracy, it won't be possible to rifle the barrel on a 3d printed gun in a way that will spin the projectile.
Folks literally etch their gun barrels with the same specs as commercially available barrels. Here is one such example from the /r/fosscad community: https://www.reddit.com/gallery/106u7au
While the fear is mostly media driven, the stuff folks are making now is a little alarming. Claymores, grenade launchers, etc. If you are interested in learning about this community, check out /r/fosscad on reddit.