I disagree with the NRA here.
If you can make them it should be fine no matter how detectable they might be.
I do wonder just how useful a plastic gun would be. Some parts need to be made of steel.
The barrel would almost certainly have to be metal. It might be possible to make a barrel out of some exotic ceramic material since we have knives now with ceramic blades but a barrel has to also withstand quite a bit of pressure.
Then why didn't you complain back in 1988?????
“Some parts need to be made of steel.”
The firing pin?