ORIGINAL: AZBear
Try using the Hodgdon H335 powder. It's a ball powder and I used to get it as army surplus...was loaded in .223 rounds as near as I could figure. It works great in my .243 with 100 gr Sierra BT bullets. I have taken Mule dear out to 350 yards with my .243 and it has killed many other deer and antelope as well. This powder works well in powder throwers and trickles like a dream.
AZ, is that a Hodgdon recommendation?