I found that 61.6 grains of IMR 7828 was the cats meow,, this only after I tested each and every listed powder charge, from start to max. None came close to the 3/4 inch groups I get with 160 grn Accubonds, and the powder weight mention.
When I got close like the OP to my OCW, I then started working my way up and down in .3 grn increments, until 61.6 turned in the tightest group at my original zero. I then started tweaking OAL..
It is a very rewarding feeling when it all comes together and you find "The One"
P.S. I couldn't get my rifle to shoot the swift bullets consistantly enough with any powder and I tried numerous powders, to continue testing them.