PLA tends to be softer, therefore it is not as strong or lasting as ABS, however it has more "give" and is more pliable.

While quite a bit of the rest of your post is reasonable, this isn't even on a nodding acquaintance with reality. PLA is more brittle than ABS, and it's made of polylactic acid – so while it might eventually break down more readily if exposed to long-term UV, outside of that context it is certainly as lasting as ABS.

"Strong" is wrong on a different axis. PLA tends to shatter under force, while ABS deforms – before shattering. ABS is nylon, after all, and we have a pretty good grasp of how nylon performs under load.

It is theoretically possible to create an FDM-deposited receiver for a firearm that doesn't shatter on the first shot. The resulting design wouldn't look like a traditional design at all, and there's really not much interest in doing so – because it is so easy to make machined gun parts from lightweight aluminum on a CNC machine.

But no one talks about banning CNC machines. Probably for the best, because then there would be no small machinist shops on the continent.