The brushed finish on these guns is done using a Scotchbrite wheel on a stand polishing machine. These are quite similar to the scotchbrite pads we are all familiar with but used a much denser material. These wheels are made by incorporating silicon carbide crystal in a polymer strand that is placed into a mold and basically compressed and "cooked". They work very well for this type of finishing but there are problems that come about when they are overheated by someone who is impatient and "leans" on the wheel. What happens is that the polymer will melt locally and the effect is that the wheel is thown out of true. So what you'll get is areas where the wheel "skips". You'll also feel the wheel start to chatter when this happens and the only way to get an even finish is by then leaning into the wheel harder, which causes a downhill spiral until that wheel is junk. BTW, these wheels run the range from about 40 dollars for a small one up to 360 dollars or more for the larger ones. I've also never been able to find a good way to resurface and re-true one of these wheels, once you burn one it's done. I once tried to re-true one of the larger wheels on a lathe using a carbide tool bit and in under one minute that carbide bit had a 1/8 inch radius on the cutting edge.
Bottomline, they had some idiot at the factory that wasn't properly instructed and he had "burnt" the wheel and kept right on working. It's also possible that some Previous Owner got his hand on one of the smaller bobs of this type for a Dremel and did the same thing while trying to re-finish some heavy scratches or dings. Point is, power tools and some people just don't mix and you're seeing the result.
