I always thought the Bizon was chambered in a 9x39mm cartridge.
Did you use a calico magazine as the basis for your Build?
This may be helpful: https://stincusa.com/bizon
Have you considered posting a price for the AT chassis? Of course, it would be without the original pistol grip (since that's being used on the Accuracy Obsession chassis).
Are the skins on the original AT chassis Sage Green?
Does it exhibit consistent POI shift in clip-on use, and how much? Does everything work as it should?
Does it include any accessories, like the Trac-IR cable, USB cable, etc.? Can these be connected to a USB external battery?