[jdougan]

Look up the WW2 FP-45 Liberator. A bad gun you could use to get a better gun. Theoretically you only need to use it once.

https://en.wikipedia.org/wiki/FP-45_Liberator

[remarkEon]

I highly doubt that anyone who 3d prints a lower does so to “use” it (I.e. shoot someone) in order to procure a better firearm.

[sheikhnbake]

The FGC-9 was used extensively in Myanmar for that exact purpose. The rebels would set up ambushes with FGC-9's and recover better firearms for future use

https://en.wikipedia.org/wiki/FGC-9#Users_and_use

[jim33442]

I would think they just print multiple guns and switch if one breaks.