bulldog284,
I've always thought Benchmark a bit fast burning for 90s. QuickLOAD seems to conform that. Adjusting various parameters to get the program to produce my 90gn Berger VLD's MV of around 2,850 fps with 24.6gn Varget, you hit maximum safe pressures on switching to Benchmark at 23.0gn and 2,782 fps.
I ran the Berger 90gn VLD at 2,907 fps last year with 25.2gn Re15, but it was a little too hot and I worried about temperature effects on pressure. If Alliant AR-Comp comes to the UK, I'll try that in the hope it performs like Re15 but without any temperature sensitivities.
To get the best out of the 90s, the barrel must be chambered just for them. My COAL with the Berger VLD is 2.715", a little less with the 90gn BT. The VLD's 0.281 G7 BC is almost identical to that of the Berger 185gn 0.308" BT Long-Range that I use in my .308W F/TR rifle at an inferior 2,785 fps, and pointing it will raise the BC to above 0.290. At 2,850 - 2,900 fps, this bullet outperforms all but the hottest 210gn .308 Win loads at 1,000yd in the wind.
I'm sorry fivering, but you simply cannot load the 80s up to match this performance. They give acceptable wind performance up to 600yd, although even that doesn't apply with the conditions regularly encountered on some of the ranges I shoot on, and the current (and continually rising) levels of competition from .308s on the new (even smaller) GB NRA F-Class short-range target, that has a 0.5-MOA V, 1-MOA Bull, then each subsequent ring only moves out by 0.25-MOA, or 0.5-MOA in total diameter. That makes the outer 1-point ring only 3-MOA or 18 inches total target diameter at 600yd and going outside that scores nothing. With only 1.5-MOA each side of the centre spot and wind conditions that switch by far more than that between shots, ones and even no score hits are not uncommon at 600yd.
The 90gn Berger BT cannot be loaded up to the same level as the VLD in my experience, maximum loads needing to be 0.5-0.6gn less and MVs around 50 fps lower. 24.1gn / 24.6gn Varget is used in Lapua Match brass behind the 90gn BT / VLD respectively with CCI-450 or PMC (Russian KVB-556M) SR magnum primers.
As noted, these loads can only be used with the 90gn Bergers VLD in a suitably throated custom chamber and MUST NOT be used in any rifle chambered for 80s or other shorter bullets. This caveat includes the Wylde chamber and similar forms, and also includes the Savage 12 LRPV and F-TR .223 Rem 1-7" twist barrel rifles unless the throat has been extended. Maximum loads in these chambers will be at least 1.0gn weight less, more likely 1.5gn with a consequent MV reduction of 100 fps or more.
Laurie,
York, England
