More truly DIY designs that use non gun parts.
This future-proofs against tyrannical legislation.
As mentioned by an earlier poster, hybrid designs with a bit of metal work/reinforcing for longevity.
I still think truly DIY designs in 9mm and 5.56mm are the holy grail, to go with 12g and 22lr. The most common, accessible calibres in other words.
More truly DIY designs that use non gun parts. This future-proofs against tyrannical legislation. As mentioned by an earlier poster, hybrid designs with a bit of metal work/reinforcing for longevity. I still think truly DIY designs in 9mm and 5.56mm are the holy grail, to go with 12g and 22lr. The most common, accessible calibres in other words.