I received a box of 6.5mm 123 grain Nosler Custom Competition bullets yesterday and I'm doing mental back flips trying to figure out what powder I'm going to put behind them.
Single base spherical powders like Winchester 748 or Accurate Arms 2520 will give me lots of velocity, but their downside is that they're temperature sensitive; the double base extruded powders are generally insensitive to temperature, though not as much of it fits in the case, lowering velocity. Fish or cut bait?
I've decided to stay with Hodgdon's Extreme lineup of powder, but I can't quite commit to a choice just yet. My options are H322, Benchmark, or H4895, all of which are made of awesome. Consulting with burn charts is about as accurate as talking to the dead, and despite there being a forum dedicated to the 6.5 Grendel, there's not much real data using any of these powders. Most folks are using IMR 8208 XBR like I am, but I came to the conclusion that though it's not temperature sensitive, it's sensitive to something, I'm guessing humidity.
There's no reason at all to not try a different powder with the new bullets, if only for the sake of science. I've already primed the once fired AA brass with (gasp!!) Federal Match primers, instead of the voodoo CCI Magnum primers that everybody and their brother uses. I've yet to see an adequate explanation for them, but that's what's recommended on every gun board. People sure can be fickle, or maybe I'm just a dumb-ass. We will soon see.
From the picture there, you can see the Nosler looks a touch shorter than the 123 grain Hornady AMAX and 123 grain Lapua Scenar, but that does come with its advantages: the super steep boattail and shorter length makes for more room in the case, which the .264 LBC is in need of. So that's the trade off -- a little more powder in exchange for a little less aerodynamics. So, fish or cut bait? The B.C. (ballistic coefficient) of the Custom Competition and AMAX is advertised at .510, while the Scenar comes in at .527, but those are for much higher velocities than the .264 LBC can give, making those numbers not as realistic as one would think.
Are you bored yet? If you haven't noticed, I'm the kind of guy who has ballistics charts just lying around. Just sitting there, all over the place. I'll find some coffee stained drop/drift table that I printed out 8 years ago for a caliber I no longer have, and after reading it over and over for a month, I realize that acquiring a firearm in that caliber will settle the problem that I've manufactured in my head. How much do I have in savings right now? Hmmmmm.
When I decide on a powder and start some load development, of course I'll take pictures and walk you through all the fun! Stay tuned!