You are arguing against a point I am not defending. I am giving a retort against your statement that you can't imagine why anyone would want a high powered rifle that had a limited reliability window. You admitted that there was a use case for it, and I called that out. That's it. I am not defending nor opposing the ability to 3D print firearms.

I don't think I actually did admit that, and I think the confusion lies in your assumption that someone who wants to do a crime is willing to accept the reliability issues. Perhaps it's worth pointing out that these reliability issues aren't simply lower n-cycles before failure. The weapon could explode on you on the first shot. The probability of this happening is lower for the less powerful cartridges (as I implied earlier but perhaps should've been more explicit). This concept of a "reliability window" is not the right way to think about this. In other words, if someone handed me a 3D printed 7.62 weapon system I would refuse to fire it, and call the person who made it an idiot.