Speaking practical, now...
I don't think asking about hobbies will work. The other guy won't know YOU are into guns, and may give a "politically correct" answer.
You need a way to let the other guy know YOU'RE into guns, so he can answer appropriately, WITHOUT offending the other guy if he's not into guns.
I propose a direct approach. Let's try some samples.
1. So, do you have any strong opinions about AR vs. AK?
a1: "What?????" You reply about ecosystem diversity in Alaska or Arkansas.
a2: "We should never send our boys to war with a varmit rifle." Bingo.
2. So, where do you stand on 9mm vs. .45acp?
a1: "What????" You then respond with something about the metric system.
a2: "Pistol development peaked with the 1911." Bingo.