600 yards is often referred to as short-range, but doesn’t look that from just in front of the main Diggle range butts. The firing point is between the right-hand edge of the reservoir and the range-house half way up the right hillside.


of nearly 1½-MOA at this range. However, it is somewhat smaller changes in the wind strength and direction that catch us out and lose points, either through being missed or seen but wrongly ‘called’ and allowed for in the shot. A fairly typical mistake amounts to the equivalent of a 1½ mph change in a quartering wind. Input this wind speed from 4 o’clock and the 155.5 combination now moves 12.16”, the 210 exactly 2” less at 10.16”, or just under 1-MOA. With the 1,000yd F-Class target having half-MOA rings, the 155.5gn load scores a ‘three’, the 210 just scrapes into the ‘four’ ring assuming the shot


was otherwise perfectly centred. The figures are summarised in Table 2 with a typical 7mmWSM load’s performance shown for devilment.


As a matter of interest, if we had adopted the commonly used ‘sights come-up’ metric, how would our two bullets compare? The high-BC / Low-MV 210gn bullet drops 375.6” or nearly 36-MOA at 1,000yd from a 100yd zero, the lower-BC / higher- MV 155.5gn bullet drops 322.5” or 30¾-MOA, thereby shooting a full ‘5¼-MOA flatter’, as most shooters would see it – potentially a very misleading result.


Getting Form These results surprised me, for while I know high-BC heavy bullets outperform low-BC high-MV combinations in the wind, I hadn’t expected it to apply here as both bullets have an identical form factor value, therefore equally efficient


in


comparison to the G7 reference bullet shape. Moving on, let’s look at the BC-mix from the other side of the equation using three 175gn 0.308” bullets. Their SDs are identical at 0.264, as are the assumed MV, but what is now different is their shapes, hence aerodynamic efficiency as represented by i7 values. MV-wise I’ll use 3,000 fps


56 Target Shooter


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