I do not believe that guns are truly an investment vehicle. Almost all the profit made in gun transactions are made on the purchase (low price because of motivated or ignorant seller).
I long ago gave up on the idea that I could buy and sell profitably. I am unwilling to take advantage of people on the purchase or overstating the value on the sale.
As for whether a gun can be brought that will apreciate at a greater rate than inflation, or at the rate of inflation, I believe the only answer might be the introductory prices CSMC has given if all discounts apply. An RBL could be a canidate for a value or an Inverness 20ga OU. That said you had to lay out some money on earlier guns from them to be eligiable and that would probably eat your margins