314-129 Reloading data

I have been unable to find specific data for this bullet.  I am currently using Fiocchi brass, 26 grains of Reloder 7, CCI #34 primers & a OAL of 2.160″.  It is swaged to .313 & shot out of a Serbian O-PAP with a confirmed groove diameter of .312 with an average velocity of 2206 fps, extreme spread 66, & standard deviation 18.  Accuracy is terrible with 8-10″ groups at 50 meters.  Normally, this rifle shoots 2-3″ groups with Hornady .310 fmj bullets at 50 meters.
  Interestingly, my first shot was a bulls eye & all subsequent shots (45 total) were without a discernable pattern.  I was shooting off a Lead Sled.  The cartridges were concentric to within 1-2 thousandths & lightly crimped in the crimp groove. I’m using Lyman #2 alloy, 30 cal gas checks & Orange Magic lube.  All bullets were 128.5 grains +/- 0.1.  The bore was not leaded & brushed clean fairly easily of the lubricant.
  What am I missing?