There is typically a special limit of a few thousand Dollars for loss by theft or mysterious disappearance of firearms however theft is usually the only peril with a specified limit, otherwise firearms are treated like any other personal property if there's a fire, water (non flood) damage, etc. Like regular personal property, if you want the antique/collectible value on the firearms then you need to schedule them on your policy, provide appraisals, etc.
I have never heard of a limit on "sporting equipment" or fishing reels although $20k in reels might be considered commercial? There are endorsements on boat policies to cover equipment specifically used on the boat (we don't do a lot of boat policies) but there's no fishing reel exclusion on a home or renters policy that I'm aware of if it's your personal property stored in your home.