Not just firearms...
My decades of working around all kinds of people have taught me a very important fact: Choose what you say at work very carefully, and who you tell it to even more carefully.
Even if the person you tell is trustworthy and has no intention of ever using what you tell them to harm you, you can never trust that person to keep everything you tell them between just the two of you.
I had several in my office, and even co-workers from California visiting here, go shooting with me. I was the "arsenal and ammo supply" for our range outings. Everyone who wanted to shoot could just show up and use my guns if they didn't own any. So, of course, there was mention in the office of shooting, but it didn't take long for me to be labeled the "gun guy."
I've seen online where many have had their hobby/preparedness used against them. One person competing for a promotion lied about the other person being considered for the promotion by saying he threatened to bring his gun to work and kill her. Of course, that never happened, and she admitted it 6-8 months later after he was arrested, had his guns taken, was fired, and had his life basically turned upside down. All because she knew he owned guns.
So, if there's no "need to know," I find it's always better to keep private things private at work. Harder to do than to say, but I found when I failed to do this, the info might be used against me in some way, whether it was about firearms, marriage, kids, etc. People who have an agenda thrive on your private information. Something as simple as joking about the "great meds" the dentist prescribed when asked about how you're feeling after a dental visit can launch untrue rumors of your pain killer addiction.
Pick your friends wisely, and keep the others in the dark. This is the best way to avoid freely providing someone info they can use against you.