Sounds like you have one of the older Knights similar to a MK85.
Tony Knight liked the Speer 50cal 325gr UniCore HP and the MMP purple 54x50 sabots. Its a good cheap bullet that expands fairly easily without blowing apart at most ML speeds. Speer Bullets #: 4495
Rainier makes a similar 50cal JHP bullet in 335gr that is a little bit tougher. MidwayUSA was selling them pretty cheap too.
$21/100
http://www.midwayusa.com/product/10...plated-hollow-point?cm_vc=ProductFinding
