Try 142SMK, 43.5-43.8gr H-4350. I seat to achieve a .010"-.020" jump. This is a long proven 1000yd F Open load for me. Treat it as at or near max, and work up. This load works in both 24" and 28" barrels.
Alternatively, H-4831 can be used, especially in longer barrels (28"-30"). Velocity may not be as fast (2850fps o/o 28" L-W with the H-4350), but accuracy could improve. I save it for light wind days.
I am setting up to replace the 142SMK with the
140SGD (Speer Gold Dot), hoping to produce a dual purpose load; for hunting, as well as accuracy shooting. I use Bushnell AR Drop Zone BDC scopes, and have earmarked an incoming 6.5 Creedmore version for this rifle.
None of the BDC scopes are intended to render match accuracy; but so far the 223's and 308 are bang on at 100yd, 200yd, and 300yd for me with loads within the specified bullet weight and velocity range. Three hits, one at each distance in the bolt guns (identical Savage 11VT's), total time well under one minute.
Current testing of the
120SGD with W-748 in 20" and 24" AR's (AR Stoner) chambered for 6.5 Grendel indicates good potential, with a goal to approximate the Federal Fusion MSR 6.5 Grendel load. My AR Drop Zone BDC scope for this one is the 308, since trajectory calcs put the 123gr commercial load at within 3" of drop as the 308/168 load at 500yd.
My reasoning employs longer barrels not to gain velocity, but to allow the same velocities at lower chamber/bore pressures/heat as shorter barrels, primarily as a bore longevity measure. My 28" .260 L-W barrel is not used as much these days, but has been mounted since about 2003. The chamber is SAAMI spec. Per consultation with L-W about throat recession at about 800rd, a 2400-ish round life span is expected. The charge weight was subsequently reduced, since I now live at nearly 4500ft ASL and am not as much dependent on velocity. Current round count is at the 1400rd range. At age 73, I suspect the barrel could outlive me.
I use BR-2's and start with Hornady 7-08 brass that is partial neck sized to 6.5mm, so the aft portion of the neck remains at 7mm, about halfway down the neck works for me. This allows the case to still chamber easily, while permitting the neck to seal decisively. Sooting is consistently stopped at the point where the neck diameter increases to a nominal 7mm neck diameter. I have removed my ejector, and the case extracts to lie in the receiver. Case cleaning consists of wiping the neck with a prepackaged wet lens cloth.
My thinking is that the neck flare more positively centers the neck in the chamber, and that the decreased length where the case is at 6.5mm results in reduced neck tension; some things that I've found enhance accuracy.
I use the basic Hornady New Dimension two dies set with the sizer body left installed.
When chambering difficulty indicates shoulder growth, I use a standard 308 F/L die with the decapper stem removed as a bump die. This is seldom required, like usually..., never.
Greg Langelius
