I'd like to interject my two cents here. I've been in the insurance business for more than 20 years as an agent and as a company employee. I'd like to set the record straight, at least a little.
First, what type of homeowners policy do you have? Is it an HO-1, HO-2, HO-3,HO-4 etc.? In Texas these go by different names (HO-A, HO-B, HO-BT,etc.) The type of policy will determine your "internal limits" on your personal property including your firearms. So you decide to just go with the "internal limits" do you know what perils your personal property is insured against?
Almost without exception personal property is covered for "named perils" only. What are named perils? Look at your policy for the list, but here are the most common: Fire, Lightning, Smoke, Wind, Hail, Explosion, Riot, Civil Commotion, Aviation, Vehicles, Vandalism, Malicious Mischief and Theft.
That's it. Nowhere, for exmple is "lost" covered. If you misplaced your firearm it won't be covered. Also note that Flood is not a named peril either.
How much will you receive if one of the "named perils" destroys your personal property? You'll get Actual Cash Value. That's defined as Cost New minus depreciation. By the way, this applies to all of your personal property. If you have a 5 year old big screen, that's what you'll get paid for, the value of a 5 year old big screen.
The best way to protect your jewelry, firearms, and other collectibles is to buy a personal articles floater or to "schedule" these items on your homeowners policy. Scheduling or buying a PAF gives you "All Risk" coverage. That means with very few exceptions-nuclear exposure, War, etc--you are covered for anything that happens including lost or flood. What the NRA sells is a PAF, USAA and virtually every other decent insurance company in America will schedule your valuables. Each company's underwriting determines what they'll schedule and what rules they will go by.
OBTW if you want to have your personal property covered for more than just Actual Cash Value you can buy a "replacement cost" endorsement that will pay "new for old".
There's a lot more to know, but I hope the above helps.