American Family here - policy came with a 5K limit on firearms and ACCESORIES (to include ammo, holsters, reloading equip, etc)
For an additional $9.00 (nine) per year I can up it to 10K - after that, it DOES go up considerably (but not much considering the value of what I'm protecting)
(I'm also a Life Member of NRA which gives additional coverage)
It's simply adding a "rider" to exceed basic coverage, just like additional insurance for jewelry, etc.
At this level there is NO REQUIREMENT (from AmerFam) for a safe, the serial numbers, an inventory - nothing... UNTIL there is a claim and then - you BETCHA' they wanna' see proof!
However, my insurance guy IS a gun-guy too and he did remind me to keep PROOF (videos, receipts, pics, etc) in a SEPERATE location other than my home/place of storage. I keep copies in my fire/water resistant safe - and originals in a bank deposit box (which was his recommendation as well)