around 0.320 at 2,580-2,600 fps MV and the wind now moves the bullet 0.84-MOA, a big enough reduction to see it fall comfortably into the ‘Four’ ring saving a point (or score a ‘Five’ in Match Rifle with its 2-MOA dia. Bull-ring). Of course, if the shot would only have scraped a ‘downwind Five’ in static conditions, 0.84-MOA deflection would still lose you two points. Incidentally, the 200gn Berger Hybrid performance shown in the table produces the same 1,000-yard wind drift as the 0.264” 139gn Lapua Scenar at 2,900 fps, a popular 6.5-284 Norma load in the early days of F-Class. .308 Win and F/TR have come a LONG way in five years, but so too has F ‘Open’ with its hot 7mm cartridges and ultra high-BC 0.284” 180s.
Readers who learned their three Rs in their school days may have noticed that there are 11 heavy bullets listed in the table, not 13. The missing couple are new Hornady HPBT match bullets weighing 208 and 225 grains. I haven’t seen any G7 BCs quoted for the pair to date, but Hornady claims G1 BCs of 0.620 and 0.660 respectively, the former a 4.4% reduction on its figure for the 208gn A-Max thereby reducing the HPBT’s G7 value to around 0.310. We can expect the 225gn model to have a G7 BC around 0.330 on that basis.
Look at the i7s and BC values, and the three older Sierras (190, 200 and 220gn models) really do look to be poor performers against the newer, longer and more ‘pointy’ designs. You might wonder why I included them at all other than to maybe warn you off wasting your money on them. Well, don’t write these old-stagers off just yet as their long-range performance is often better on the target than on the ballistics program printout. The high i7 figures derive from their short blunt nose sections, and that’s certainly what determines drag at very high MVs. But these bullets have a reputation for really performing at the far end of the flight as velocities drop and the nose-form becomes less important. All three were very popular in Match Rifle until recently – and still have their adherents – as they perform to 1,200 yards and beyond. It seems their transonic zone performance is better than that of many of the long nose types, and they’ll even pass through the sound barrier into subsonic flight without a qualm. Much of this must be down to that enormously long 9-degree angle boat-tail rear section, and they seem to be very well balanced too enhancing stability through a wide
71
THE HANDLOADING BENCH
308 Winchester Rides Again Part 3 By Laurie Holland
Same (.308 Win) cartridge; same (Norma) case; same (208gn Hornady A-Max) bullet; two noticeably different COALs. The reason will be explained next month.
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