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20% greater, should see a ~5% MV increase.


I’ve assumed a 6BR rifle with 28 inch barrel running at sensible pressures will give a 105-108gn long-range match bullet ~2,800 fps MV, so our hypothetical 20% larger cased cartridge will produce an extra 140 fps but at the cost of more rapid barrel heating and fouling, heavier recoil and more rifle disturbance on the rest and bags, much shorter barrel accuracy life.


With the small BR case, expansion ratios are low even in 6mm, so extra long barrels aren’t needed to produce top MVs, 28 inches reckoned to be optimum for target rifles and less than 10 extra fps available for each inch of barrel above that length. While the MV lost with each inch lopped off below 28 inch will be greater, it’s still modest compared to most high-performance cartridges, so a 25 or 26 inch barrel multi-purpose rifle that will do the business on long-range targets, vermin and small deer species is perfectly feasible.


While the 6BR only had the .243 and .308 Win cartridges, plus maybe 6.5X55mm to contend with 15 years ago, we have a much larger choice now starting with the 6PPC and going up to the larger 6.5mm cartridges such as 6.5-284 Norma in relatively small


capacity steps. I reckon there are some 20 models readily available across the two calibres if you count Ackley or other ‘Improved’ versions separately.


Table 2 lists the main members of this combined 6mm and 6.5mm group, and one must particularly bear in mind the competition provided by new smaller capacity 6.5s, the 6.5X47mm Lapua and 6.5mm Hornady Creedmoor, not to forget the revitalised 260 Remington, which finally has top quality (Lapua) brass available. They give 139/140gn bullets comparable MVs to the 6BR ‘family’ but use higher BC bullets (Berger 6mm 105gn VLD: 0.272 G7 BC; Berger 6.5mm 140gn VLD: 0.313).


Table 3 compares the external ballistics performance of the 6BR and 6mmDasher against these smaller 6.5mm cartridges. The cartridge was popular in the early days of F Class but has been rudely elbowed off the ranges - at National GB League level anyway - by much more muscular numbers, first in 6.5mm calibre and since 7mm. The 6BR is still often viable in club and regional level events and it is notable that many continental European visitors bring ‘sixes’ to the annual GB F Class Association European Championship weekend at Bisley - the multinational ‘Sixes’ winning the 30-round Rutland team match (15 each at 900 and 1,000yd) with a score of 557.50v ex 600. Team member Christer Jakobson from Sweden shot the only ‘possible’ in the competition with a 6XC chambered rifle.


There is some home-grown competition too of course as the BR is very susceptible to ‘improvement’. Of the various forms, the best known are the BRX and Dasher that see neck length sacrificed to allow a considerable degree of fireforming that moves the shoulder forwards and also reduces the case-body taper. This increases the case capacity by some 3 to 3.5gn if measured using the weight of water the case holds and offers 100-150 fps extra MV with a 105gn bullet.


The main difference between the two forms is shoulder angle, the BRX retaining the parent case’s 30-degree and allowing standard dies to be used, the Dasher providing a sharper angle. There is also the BR-DX form that doesn’t see the shoulder move forward but provides a 40-degree angle and a bit less body taper for maybe a 1.5gn capacity increase. This trio have a reputation for providing superb accuracy as well as MV improvements, maybe even better than that of their parent, and are widely used in American 600 and 1000 yard benchrest competition.


Shooting Sticks It’s no coincidence that the cartridge’s popularity has grown alongside the huge increase in the number of custom-built precision rifles that have been commissioned in recent years. Even Remington, who’d adopted the cartridge,


Target Shooter 55


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