Will, apart from what has been said, for an insurance valuation there are a couple of points .
Do you need to show a written valuation or other documentation as or its purchase price ? If not then assume it is in reasonable shootable condition and use that as the basis of what you would expect to pay for similar gun to replace it . Look on any of the sales sites for current asking prices.
There are 3 values a gun or any other object has,
1 what you would pay over the counter in a store .
2 what you would insure it for if it needed to be replaced ,add about 20%.
3 how much you could get for it if you have to sell it today /now.
A way you could determine an amount to insure .At the moment it stands you at $350 assume you spend $500 on it which will add value so that $850 plus say 30% , that comes to $1100 .If you feel that is realistic then that's the value to insure.
