Like you said only CCM and AKA make Bushmaster threaded feednecks, the promaster section of PBN is full of: Why did my feedneck fall off? Why won't it thread in? etc. The answer is always the same, you didn't read the stickies and stripped your body. You've also got to watch out for the people selling feednecks on Ebay- they have no problem calling the SP threads and BM threads the same thing.
Everything Ebay has that for the marker:
bushmaster feedneck items on eBay.com
Just don't go for those warrior feednecks or the no brand ones up top.
Penguin
Edit: I don't know if CCM makes polished red feednecks. Those are all factory direct so there might just not be a demand for them.