Your Knight bore is slightly oversized
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. The Extremes and Elites are button rifled and inside diameter has to be kept from .499" to .502".
I believe its another internet myth. As you say, triple, advise on the internet is worth what you pay for it.