I just started working up the 143 ELDX for my Desert Tech. Looks like ~41.9 gr of H4350 is going to be the sweet spot at about 2825 fps (26in bbl).
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I started them at about .03 off at 2.197 (to ogive). I’ll run another batch at various seating depths to fine tune it.
I realize this probably doesn’t help you much since you’re using a different powder, but I’ll post my stats for reference:
Bullet: Hornaday 143 ELDX
Case: Lapua
Primer CCI 450
Powder: 41.9 grains, H4350
OAL (to Ogive): 2.197
Barrel: 26in Benchmark 1-8
Velocity: ~2825fps (Magnetospeed)
-- Below is my current secret sauce. I’m moving to the Eldx because while the Scenar drives tacks, it doesn’t kill very well.
Bullet: Lapua 139 Scenar
Case: Lapua
Primer CCI 450
Powder: 42.6 grains, H4350
OAL (to Ogive): 2.220
Barrel: 26in Benchmark 1-8
Velocity: ~2866fps (Magnetospeed)