I’m writing this article to follow up on a couple of comment threads that I’ve seen at SurvivalBlog: To have a substantive long range accuracy advantage over .308 Winchester, requires 6.5 Creedmoor to use the 140 grain bullets that have accurate loads that are more often then not, are typically at velocities of between 2,600 to 2,700 fps. The low recoil advantage should not be underestimated. However this advantage is easily offset by the much longer barrel life of barrels chamber in .308 calibers. However, exceed 2,900 fps (feet per second) in .308 diameter barrels, and barrel wear is greatly accelerated.
Because in my area it is difficult to find 500 yard shots, and I had the old trusty 6.5×55 Swedish Mauser (SE) rifle, I duplicated the 7.62 NATO Match load trajectory of the 168 grain .308 bullet at 2,650 fps, with a very mild recoiling 123 grain 6.5 bullet at only 2,601 fps. Even with a worn barrel, this custom load for this barrel produces Minute of Angle (MOA) accuracy. As the barrel wears, the load will have to be changed. Starting out with an MOA load, the old Swede will stay accurate enough for 500 meters for significant time. The ballistic coefficient of the 123 grain AMAX and SST bullet is .510, a tad higher than the B.C. of the 168 grain .308 bullet that is usually around .475. The result is a near perfect match in trajectory as determined by a ballistic calculator.
This was done to match the calibration of the BDC (ballistic drop compensator) military style ‘turret’ scope set up for this trajectory. It has the markings on the external dials in meters, and can quickly be adjusted on the fly as targets may present themselves quickly at nearer, and farther distances. This is intended to be a poor man’s DMR (Designated Marksman Rifle), that really should be a semi auto, but this is what I got. The result is also a recoil that is so mild, roughly 11 lbs, and on par with the .243 Winchester, that the hit can be seen in the scope every time, eliminating the need for a spotter. And therefore, the follow up shots are more accurate, as the shooter can see his misses and corrects his aim, and can get back on target quicker.Continue reading“Sensible Long Range Cartridges, by Tunnel Rabbit”