With all that has been going on these past few weeks, that is not a surprising response. But I am guessing in general she would react to that.
There is nothing wrong with having a special interest in firearms. They have just been lumped with very negative stereotypes which completely ignore how they are really supposed to be used and how interesting they really are.
Perhaps you can try going more subtly until you are free to explore all on your own? For example, I have been obsessed with death since I was 3 (try that for casual conversation) - but I satisfy the obsession by intertwining it with other things: mythology, movies, awkwardly deep short stories, etc. So if you have lesser obsession you can work with, perhaps try working with that.
Don't hate yourself for having something you genuinely enjoy - that is like hating yourself for being happy.