I really like the NRA insurance. As long as my individual firearms are under $20,000, I just give them the make/model, and any accessories that attach to the firearm. No serial numbers, no goofy business. That's great, because AR15s and similar firearms can swell to 2-3x their base value based on the scopes or widgets you upgrade them with. According to the fellow I talked to on the phone, NRA's insurance covers aftermarket parts, gunsmith work, scopes, barrels, etc.
I would fathom traditional insurance would only give you base value, and only if you provide serial numbers, go on a date with their ugly best friend, and provide them with your social security number.