But now you're talking about detecting a nail. Which if you decided to ban (somehow?), you'd still be tasked with detecting a tiny object. Most metal detectors are tuned not to even care about normal size belt buckles as far as I know.

I hadn't thought about that but it makes sense. I wonder if there's any type of plastic filament that could do the job.

> I wonder if there's any type of plastic filament that could do the job.

On a practical note, probably not: the designers probably tried really hard to make a fully plastic gun - they took the trouble to make the barrel out of plastic - but didn't. Stands to reason that it's due to necessity.

At a more theoretical level, I think you'd find it exceedingly difficult to trigger a primer using a material softer than the primer itself.

I'm sure it's not impossible - for example, you could probably trigger a primer by shooting it with a plastic bullet - but within the engineering confines of a handgun it seems implausible, particularly since the easy solution, using a nail, is so readily available.

What about ceramic, glass, or heat activated?

some landmines use glass ceramic firing pins, according to wikipedia.