Knight will tell you that if you load 100 grains of powder and a Knight Red Hot bullet of 250-300 grains of weight and it does not shoot accurate, then something is wrong with the rifle.

My Disc will shoot a number of things well. Depending on what I shoot the powder charge changes. I normally shoot Pyrodex RS out of the Knight Disc with a Winchester W209 primer. Try 90 grains of loose powder and a 250 grain Shockwave. They shoot well for me. Barnes Expanders in 250 grain also shoot good, but I kick them up to 110 grains of powder. When I shoot the 240 grain I drop down to 80 grains of powder.

All you can do is try some different loads. If you have the Mag 240 XTPs lower the powder charge once and see if they do not start behaving better.

Also on my Knight, if I do not swab between shots, then there is very poor accuracy.