Bullets on a airplane

I once had a few bullets from 45 on my carry on without knowing. I flew from Phx to Florida and I flew back not knowing I had that in my bag. Once I got home & I unpacked I realized I was traveled with them on me the whole time. I kept wondering how they didn’t explode once up on the plane & why didn’t TSA stop me or say anything to me? What’s your guys thought on this ?