.308 Marlin Express (using Hornady bullets)
Date: Oct 21 2014
The .308 Marlin Express was introduced in 2007 as a joint effort between Marlin Firearms and Hornady Manufacturing. The year prior, Hornady began offering Flex-Tip bullets in .30-30 Winchester factory loads. These spitzer profile bullets feature a soft rubber tip that allows their use in tubular magazines without resulting in primer set-off. The next logical step was to create a new cartridge that would offer greater performance than the .30-30 WCF while using the Flex-Tip technology. The .308 Marlin Express was the result, which comes within approximately 100 fps of duplicating .308 Winchester ballistics (when both are used in a 22-inch barrel).
The new cartridge is based on the .308 Winchester case, but features a semi-rim for proper function in lever-action rifles and has been shortened (1.920 inches) and retains the same 20-degree shoulder. Shortening it allows use of low drag 140- and 160-grain bullets that offer a high B.C. of .335 and .395, respectively. (Note: These are different than FTX bullets designed for the .30-30 Winchester and should not be interchanged.)
Due to the straight-pull nature of the Marlin extractor, which does not have the same camming power associated with a turn-bolt action, maximum average pressures are limited to 47,500 psi. At this pressure level, cartridges extract smoothly and reliably. Another feature that helped achieve targeted ballistics was the development of a new propellant specifically engineered for this application.
Current Hornady factory loads advertise a 140-grain MonoFlex bullet at 2,800 fps, or a 160-grain FTX at 2,660 fps, while Remington offers a 150-grain Soft Point at 2,725 fps. From the 21 ¾-inch barrel of a Marlin Model 308MX test rifle (factory listed at 22-inches), velocities clocked 2,720, 2,585 and 2,626 fps, respectively.
Although several powders gave excellent accuracy, including IMR-8208 XBR, Hodgdon Varget, H-4895, Ramshot TAC, Accurate 2520, Winchester 748, Norma 203-B, Alliant RL-15 and Power Pro 2000-MR, Leverevolution yielded the highest velocities and closely duplicated factory load performance. Most loads using the 140- and 160-grain Hornady bullets proved capable of around one inch 100 yard (three- and four-shot) groups with the aid of a scope.
Cases should be full-length sized to assure easy re-chambering and bullets should be firmly roll-crimped in place to prevent being deep seated when subjected to magazine spring pressure and recoil.