Wildcatters and cartridge tinkerers seem never to be satisfied with the performance of factory built ammunition thinking they can always do better. In some cases they can, as is the case in many of P. O. Ackley’s designs; however, often their efforts go unrewarded because only marginal performance increases are attained.
Imagine our surprise when we discovered that by making some changes to the 300 Weatherby case design which increased the case capacity by 3.5%, we gained 26% in energy! Now we had 300 Weatherby or 300 H&H muzzle energy and velocity almost 200 yards or 350 yards respectively downrange using 180 grain bullets! This realization prompted a patent application in the spring. The table below illustrates the ballistic comparisons of the 300 Coby Ultra Magnum vs the 300 Weatherby or 300 H & H with 180 grain bullets: