18” ballistic advantage 6.5 CM barrel October 08, 2017, 11:18:59 PM I got a 18” ballistic advantage barrel (premium series) on my diamondback AR10. I broke it in with hornady whitetail using BA’s suggested break in. I then started loading the 143 eld-x’s with H4350/federal match primers @ mag length 2.805”. Shot 5-5 shots groups at 40, 40.5, 41, 41.5, 42g. Best group was 1.4” at 100 yds. Other 4 groups were 2”+. I received my hornady modified 6.5 cm case and measured. To the lands was 2.892” so in the mag 87thou jump. I read these bullets are jump tolerant. Should I try seating even further to see if the grouping improves. A friend suggested shooting 139g Lapua Scenars. Any others using these in a ballistic advantage barrel.