I'm not a big fan of riders on my insurance policy. I've been there and take a dim view of their value. I originally started with riders which covered my wife's jewely. All the jewely needs to be professionally appraised first or you may never be able to substantiate their value in the event of a loss. Any custom rifle or any rifle with any custom work will also require some documentation as to its current value.
The real problem is that the insurance premium is based on the total value of the insured property. A 10% annual premium is not all that unusual. Given that figure, you would be paying for your firearms
TWICE in the first ten years. To make paying this premium a logical decision you would have to anticipate that your total collection would be stolen
MORE than once every 10 years.
Even if you only paid 8%, you still would suffer the same dilemma, however you would repay for your firearms every 12 years instead of every 10 years.
I would much rather put the insurance premium money into a quality gun safe. Buy a large one so that you have plenty of room for some jewelery, documents or whatever other new purchases you may make.
Just my 2 cents - VH