I've had two of these; still have one. old70's experience with the cartridge is similar to mine. The Hornady, Speer, and Sierra 100 grain SP flat base bullets and H4895 work well. A couple of other good ones are the Sierra 87 grain SP and 90 grain HP, again with H4895.
I've tried other powders including Varget, Reloder 15, H414, and IMR4064. They will often work fine, but I've found no single better powder than H4895 for the 87-100 grain bullets. My work with bullets heavier than 100 grains in the .250 has been very limited, but some old notes indicate good accuracy with IMR4064 and the 117 grain Hornady round nose, chronographed muzzle velocity around 2,500 fps.
Considering the very slender contour of the barrels, these rifles can be surprisingly accurate.
