Long ago,, I had to use the NRA member firearm insurance. It was a smooth & well handled event. Police report, documentation, and I got a check.
I also have added additional insurance via the NRA & haven't had the need to question them. One thing I do like is that you do not have to submit a "list" of your firearms for them to be insured,, UNLESS an individual firearm exceeds $10,000.00.
But a scheduled list, kept up to date with details is very important to be able to provide the police & insurance company with any loss.
Plenty of details,, and especially photographs is an easy way to prove what you have.