So I don't think Knights drilled the hole wrong. The dimensions of the roll pin are only slightly larger. I found this: https://www.operationparts.com/knights-armament-sr-15-bolt-catch-roll-pin/
The DPMS Lower Kit is maybe low budget but has proven itself in my other 3 AR lowers. I measured the holes for the takedown pin. They are 0.27in. On all my other Ar15 (Windham, HK, Sig, Aero) the measure is 0.25. On the Net I read that 0.25 in (for the pins) is Mil Spec. In contrast to the others, the knights lower wobbles strongly. I wonder if this is wanted for military purposes or if pins larger than 0.25in have to be installed here which are then not compatible with other uppers than knights.