You should also consider the Speer Gold Dot (now called Deep Curl) 300gr .452, which looks similar to the XTP, and similarly priced. As for the sabot for either, in Harvester, try the crush ribbed black (H25045SRR) which should fit down your barrel pretty easily. For the bigger bullets, like 300gr, you should also consider the Harvester long black sabots (H5045 LB). They are harder to load, but did give me greater accuracy in my Omega.

Unfortunately, you will likely have to do some experimentation to find out what works best in your barrel.