Interesting that while you apparently trust the TSA screeners for nothing else you are trusting them to do something which is beyond the capability of the technology in use.

Guns are probably the easiest weapon to detect on the Xray though the detection rate can be reduced by careful placement and surrounding them with material of similar density.

Explosive devices, on the other hand, can be made of items that look quite routine in a piece of luggage. That is why they are using the sophisticaed 3D MRI-type machines for screening checked luggage and even those are unable to completely clear all bags.

But you already know that, you just choose to ignore it.