I was taking them at their word that they fired 30 rounds through it after doing the work. Given chambers as rough as you describe, they should have had difficulty with ejection/extraction during those 30 rounds which makes it unlikely that they would have continued to the proof test and then let the gun out the door.
So I'm guessing they didn't test fire the gun. Either that or they had to beat the cases out of the cylinder and still figured that wasn't going to be an issue for the purchaser...
