Until I retired, I was with that "Good Neighbor" company for 44 years. I owned firearms the entire time, and reloaded most of that time as well.
Our standard homeowners and renters policies automatically include some firearms coverage, and we willingly provided additional coverage, including additional riders to provide higher and broader coverage. We also assumed that most gun loonies, like me, reloaded. If so, we presumed most clients were responsible and took the most basic precautions. We also, if asked, provided specific coverage for reloading equipment (ask your agent for a "personal articles floater").
Argay is right: ammo in a box doesn't behave as it does in a gun. You can test that hypothesis by throwing a loaded cartridge into a campfire. It'll pop, the bullet will fall out of the case, and you'll be left with a story to tell how stupid you were when boozing on that elk hunt (seriously, don't do this).
Smokeless powder burns, even when enclosed in a cartridge case and doesn't explode. It burns fast, but that's the subject for about a bazillion other posts.
Black powder? Now that's different. It does blow up. In either case, it's good to let firefighters on the scene know about your hobby. No, they won't let your children, dog, cat die because you reload for a hobby.
Although......I do recall an instance some years ago, when, after rescuing the owner, a local fire department stood deliberately some distance away and allowed the house to continue burning and blowing up. In this case, the homeowner, a survivalist-type, in addition to his reloading equipment/components, had also stocked artillery ammo, dynamite and plastique. The photos were pretty dramatic, as were the burns over 90% of his body. But even then, the home was covered by his insurance (yeah, I was happy he wasn't one of my clients).
I can't speak for other companies, but because of state codes, insurance policies are almost entirely uniform in word and scope, with little variation throughout the 50 states.....therefore, I'd be surprised if my answer doesn't apply to most other companies' policies as well.