Again, in that few of times and since it was a coated piece then it's doubtful that you have harmed anything. Visual inspection of the crown should do. Use a magnifying glass and give it a close inspection to make sure you haven't worn a spot in it. The bore side (throat) is harder to detect sometimes. Just look for anything that might look "off" using a bore light or a flashlight shining down the muzzle. I buy a LOT of Mil Surp. rifles and invested in a bore cam. Makes life MUCH easier at trade shows and such. Again, in the few times you have done that, it is EXTREMELY doubtful that you have damaged anything. Many people go for years without using a bore guide and don't really hurt their rifles. Like Mercy said, most damage in the throat comes from the joints "clipping" the edges and damaging that way. Damage to the crown comes from rubbing the rod along it . Most crown damage I have seen from cleaning rods was at around 7 o'clock from right handed shooters and 4 to 5 o'clock from lefties. And usually from years of improper cleaning methods.