Home Forums Reloading Big Game Rifles Good 6mm AR / 6mm Grendel / .243 LBC loads

So, this thread is a bit old, I know. I got a 6mm Predator (same as the 243 LBC and 6mm Grendel, just different name). While messing with that (and because of that), I've started using my 6.5 Grendel for hunting again so I've been messing with loads for it. Certainly there are differences between the 6 and 6.5, but basically they're the same case and will have "close enough" loads to indicate at least a useful comparison of powders.

With that said (and this: this is about the 6.5 Grendel and presented only for reference purposes, not loading): I loaded for 95gr Hdy V-Max. I like CFE223 in general and find that oftentimes it lists with the highest published muzzle velocities for a given cartridge/bullet combination, so I tried that. I also tried 8208XBR and Benchmark. After reading this thread, I tried Leverevolution. For the 95gr Hdy V-Max in the 6.5 Grendel, 8208XBR gave me the highest velocity (2,832 FPS from a 16" barrel) with (for me) an acceptable level of primer flattening (not too much). CFE223, in the amount I tested up to, gave me too much primer flattening and not as high velocity. Same, too, with Benchmark. When I tried Leverevolution, I found a load listed online and went under that quite a bit "just in case the Internet lied". I worked up to the listed "max". With all powders I found some ejector swipes, some more than others, but I've since attributed this more to gas system timing (having shot some of the same loads in a 6.5 BPC bolt action rifle now)...except the Leverevolution...no swipes. With the Leverevolution I had rounded edges (not flattened) on the primers all the way to the listed "max". I then loaded beyond the "max" load, incrementally, to 32.5gr Leverevolution. At that amount I started seeing a little flattening of the primer and some ejector swipe (still, I think that's timing of the gas system). The muzzle velocity on the hottest load (32.5gr) was just over 2,700 FPS, about 125 FPS below what 8208XBR could give me. At 32.5 grains of Leverevolution, the case is nearly full. All loads of all powders were ignited with CCI #41 primers (per CCI, they are to be treated as "magnum" primers).

The takeaway from this: in a nearly identical case to the 6mm LBC/Predator/Grendel, 8208XBR gave me the highest velocities while remaining within my tolerance for pressure signs. Leverevolution gave acceptable velocities without exhibiting as much (if any) pressure signs. The 0.243" projectiles have 15.28% less bearing surface on their butt end than the 0.264" projectiles. That means less applied force during firing, if the chamber pressure remains the same. Therefore, acceleration of a similar-weight projectile should be slightly slower, given the same chamber pressure. Therefore, a slower-burning powder like Leverevolution, may be preferable. I say "slower burning" because, by the evidence I saw of pressure signs, the Leverevolution gave similar muzzle velocity (125FPS difference in the 2,700-2,800 FPS range is small), yet less primer flattening. Conjecture then: if 8208XBR gives better velocity than CFE223 in this load and Leverevolution gets close to the same velocity yet exhibits less pressure sign, then Leverevolution may yield higher muzzle velocity, or close enough as to make no difference, in the 6mm variants where there is less applied force (given the same chamber pressure) to the projectile hence slower acceleration while, hopefully, still exhibiting less pressure sign.

FWIW. YMMV. EIEIO.

--HC