March 11, 2019
Sometimes you find a cartridge that really shines when it's handloaded, and it reinforces the notion that reloaders can improve the performance of their chosen cartridge and firearm. The 6.5mm Grendel is just such a cartridge. In fact, the fantastic performance my 6.5 Grendel handloads exhibit has helped change my view of a certain firearm platform.
I admit that from the first time I shot a firearm I've been a traditionalist at heart. Blued steel and a nice piece of walnut make me happy. And although I have acquired a few AR-style rifles - and handloaded for them and shot them - I tend to gravitate back to my comfort zone: blued-steel and wood-stocked rifles.
Over the years I've worked with - and have come to appreciate - some of the traditional semiautomatic-rifle cartridges, including .223 Remington/5.56 NATO, 7.62x39 Soviet, .308 Winchester/7.62 NATO, .30-06, and 6.5mm Grendel - but mostly only in bolt-action rifles. I don't own a Garand or an M14, and my Ruger Minis are still nearly unfired. Heck, my first experience with the 6.5 Grendel was in a rebarreled Savage bolt rifle.
There's no need to recount everything that's been written about the origins and relative merits of the 6.5 Grendel. Many scribes have earnestly spilled their guts with extraordinary rationales and statistics supporting the cartridge. Simply stated, it's a slightly enhanced 6mm PPC case necked up to load .264-inch bullets. The increased caliber allows the Grendel to launch bullets weighing from 90 up to 129 grains with exemplary results. According to several knowledgeable folks, it should have already replaced the 5.56 and 7.62 NATO rounds as the U.S. military's service cartridge.
Reloading the 6.5mm Grendel
As I said, my first experience with the 6.5 Grendel was in a rebarreled bolt-action rifle, but recently I used a Sun Devil SD15 AR-type rifle for a couple of handloading reports for the Hodgdon and Lyman reloading manuals, and because the Grendel was so accurate in my bolt gun, I purchased a 6.5 Grendel upper for my SD15 to see what handloads could do in it.
Handloading the cartridge for my new AR upper was pretty straightforward. I tried chambering a few cases I'd fired in my bolt rifle, but the headspace was a bit too much to ensure reliable functioning in the AR. So I selected 20 pieces of brass and, by trial and error, readjusted the sizer die until I achieved the proper chamber fit. Maintaining headspace is always important, but it's critical in an autoloading rifle. Unlike in a bolt action, chambering and extracting the cartridge/case is not augmented by muscle power. For reliable operation, the cartridge must readily "fit" the chamber and, when fired, must provide internal ballistics compatible with the rifle's self-loading operation.
In addition, managing the propellant gases for reliable operation is a primary consideration for an autoloader, and since it has been a few years since I handloaded for the 6.5 Grendel bolt gun, there are now several new propellants from which to choose. Hodgdon has CFE 223 and LeverEvolution. Alliant now offers AR-Comp and Power Pro 2000-MR. IMR-8208XBR also is a good choice. I'd previously used Accurate 2015, 2495, and 2520; Alliant Reloder 10-X and Reloder 15; and Hodgdon H335 and Varget. Some of my better Grendel recipes included Ramshot TAC and VihtaVuori N540.
As the load data chart below shows, these propellants and several match bullets performed quite well in the Sun Devil rifle. The load consisting of theBerger 120-grain BT Target bullet over 27.5 grains of Accurate 2495 BR was the one that really changed my opinion of AR rifles. Five rounds grouping under 0.25 inch will get any casual shooter's attention.
I built additional loads with the same propellant charge and two different bullets, and groups still ran consistently from 0.75 inch to just under an inch. I couldn't measure pressures, but the primers and cases indicated cutting the charge a half-grain would be prudent.
I'll say it again. The performance of the 6.5 Grendel handloads in my Sun Devil SD15 has helped change my interest level in AR-15 rifles. I still enjoy handloading for and shooting my blued-steel/wood-stocked bolt actions, but now I know just how good these modern sporting rifles can be.