Trying to guess how many rounds were fired based on fouling is kind of tricky unless you know exactly what kind of ammo was used. I used to be able to buy one brand that would foul less in 200 rounds than my more commonly preferred round would foul in a couple of cylinders' worth.
If you know what the test ammo they use was, you can get some (preferably from the same lot), take pictures of the current condition of your gun, then clean it very thoroughly, then shoot the test ammo until you reproduce the conditions you saw in your original picture. That will give you a reasonable estimate of how many rounds were fired while testing the gun.
My question is, "What are you going to do with that information?"
I seriously doubt you will convince Chiappa to alter their test fire procedures. Most people are probably happier about having a manufacture test a gun thoroughly given the problems with getting one fixed if it comes to them defective. Especially an imported firearm.
If you're going to try to prove the gun is not new, doing so based on an estimate of how many times the gun was fired before you got it probably isn't going to get too much traction unless you know with some reasonable certainty how many times Chiappa says they shot it. For example, if Chiappa said they didn't do any test firing at all, or only fired a single round, then you might be able to at least make a complaint to the gun store to see what they would say.
So, how does it shoot?
