I've done that too. You travel so aggressively, eventually you have some oopsies.
I went through a stint where I was driving for work, and working with a bunch of people in a woodsy state. A guy would take us shooting, and he asked me to buy a box of ammo to replace what I shot - so 20 bucks for 500 rounds of .22 caliber ammo.
Next time I flew was the first time I had actually been selected for TSA precheck - you know, the Trusted Traveler program and you can guess what I left in my carry-on. I was very apologetic and had to talk to a very grumpy city police officer, but it was fine. I paid a fine of $130, and that was it - they offered to let me check my bag to keep the munitions too!
It has never even come up with my 3 Global Entry interviews either. And yes - I live in a blue state.
Obviously don't do it. It wasn't a problem for me, but very much YMMV. I know someone else who got dinged for having a banana they bought in a foreign airport, and that continues to come up in their Global Entry interviews. Live ammunition < Bananas, apparently.