ORIGINAL: Roskoe
It is a .40 caliber. I also called the Colorado Division of Wildlife law enforcement unit in Denver last week. They confirmed that, while sabots aren't legal during the regular MZ season, any .50 caliber rifle that shoots a bullet of 170 grains or more is OK during the rifle season - regardless of the sabot.
When you talked with DOW, did you clarify if you would hunt deer or elk? The reason I'm asking is that the minimum weight for .45 and below is 170 for regular season deer and this weight is not legal for Elk, at least for regular ML season. During the regular ML season, minimum weight is 220 grains for Elk as it is also the minimum weight for .50 cal.
On the other hand, the DOW requires a lighter minimum weight than that for centerfire rifle and "only" 1000 ft. lbs at 100 yards. Your load blows that requirement out of the water. Even so,I just wanted to ask so that you don't have any problems when you come to hunt in Colorado.
Happy Hunting, Phil