If you join the Field & Game you can insure you firearms through them with your renewal. You get 1 shotgun include free with membership. Ring and ask as I could find nothing about it on the web site.
Field & Game

FG,
The SSAA Insurance standard house and contents policy offers unspecified [i.e. don't require individual item valuations and details] firearm cover, with a cap of $1500 per item and $10k total.

Anything above that requires individual listing in a policy schedule, as 'specified items'.

The policy also covers contents 'temporarily removed' from the house for up to 35 days in any one policy year, anywhere in the world.

Another thing they look after is ensuring that no 'exclusions', for having stuff like powder and primers around, get imposed by the underwriters.

I have had that happen with a motor vehicle policy - broker changed underwriters, and the new one had an 'exclusion from cover' where 'dangerous goods' were being carried. The way it was worded, putting a BBQ gas bottle aboard would have resulted in no cover! Changed brokers quite smartly that time!

Cheers,
Doug