Sorry, no real-world experience, but have experienced several LWRC rifles before...and I run factory 120 SST almost exclusively in my Ambush Arms.
There is no reason why that combo should not shoot better than 2 MOA...meaning that under controlled range conditions I'd bet a paycheck you'd get groupings better than 2.1" at 100 yards. Chances are that the groups would be considerably less than that...BUT, each barrel is a little different and may exhibit preferences towards something else. My rifle is 1 MOA with the SST, and that's why I run it.
However, accuracy under field conditions is far more important. It is nice to know though that the reason you missed is because of the shooter and not the gun/ammo combo.