You are the one who wants him to change. So you need to do some work here. Get interested in guns.Our lives are spent in so much silence. We have been married for 30 years. We do all the things the stupid marriage books tell me to do: we have weekends together, we speak respectfully to each other, we share some hobbies, we do charity work together... Yet I spent 10 hours in the car with him yesterday to such silence and it is always that way. I will try to say something and he gives a brief answer. I ask him to expand and he will a little, then silence again. I can chat on and on about my job, but I don't think he is very interested. He can chat on and on about guns, but I could really care less though I try to ask questions but it just doesn't really interest me.. So I'm faking it. Our sex life stinks. We went away for a little vacation and got back yesterday. No sex at all. I'm so bored and lonely and I cannot wait for my job to start again.
I assume he owns some guns. Ask him to talk you shooting. Get involved in it as a sport with him. Then once you have his attention, you can slow draw him towards things you are interested in.
You might benefit from the book "Divorce Busting"... yea I know you believe that marriage is forever so the book title is a turn off. But what the book talks about could help you.