It took some work, but seem to have found a mag length load. If initial performance continues, this will be the singular load for this rifle as JLK bullets can be used for both targets and hunting.
In load development, was pretty much set on the 130JLK, H4350 and Lapua brass. This left charge weight and primers as the variables. Tried F210M, CCI BR2 and Fiocchi primers. Fiocchi provided a consistent low ES across multiple charge weights of H4350. Thanks to ICANHITHIMMAN
in a previous post in this thread suggesting Fiocchi primers. My load development had me focusing-in on F210M and on a whim, tried the Fiocchi. So far their performance has been great.
Here are the details:
Bullet: 130grain JLK
Powder: 45.4grain H4350
Primer: Fiocchi Large Rifle Primer
Brass: Lapua (love it that Lapua came out with 260 brass!)
ES = 5
Accuracy = .320moa (pic below)
Used this load at an informal tactical match this past weekend. The load performed well out to 700+ yards.
Ran the ballistics on this load and with the 130JLK going 3005fps, it is a deer killer to ~900 yards.