This was true at one time when they used cut rifling on the LK's and MK's, but I am not sure thats the case in the last 5 years. I sluged my disc and came out right on target.
Your Disc is not of the normal variety. Further proof that Knight has not changed for the past five years was their plea to Powerbelt Inc. to offer a wider variety Powerbelt bullet in the green packages that stated for use in ALL muzzleloaders. That was 100% Knight's doing.
I do agree that in the past 12 months, tthat Knight Inc. may have reduced their bore sizes in the new Discs. Not sure thou... just another one of those internet rumors........