Just to put a bow on my experiments with Re26 and QuickLoad, I've looked at it with the 300 magnums and the .338 WM. In both it produces the highest velocities of several appropriate powders for these cartridges at 60,000 PSI pressure. The key factor with this powder (and any powder actually) is the expansion ratio (ER) of the cartridge. With cartridges having lower expansion ratios (those approaching overbore capacity), Re26 is the best powder available for velocity. In fact, cartridges with an ER less than about 6.70 are ideal candidates for the powder. However, once you get to higher expansion ratios, its effectiveness declines. So for the 30-06, with an ER of 6.99, Re26 is not optimal. You can't get enough of it into the case to get pressures up to 60,000 PSI without excessive powder compression (113% load density behind a 180-gr. bullet). Faster-burning powders like Re22 and Norma MRP do better as they produce equal velocities with only minimal compression (104%). And once you get to the .308 Win., with an ER of 8.61, Re26 is completely useless, as you can't get anywhere enough of it into the case. To clarify, I consider powder compression of up to 105% load density acceptable, but prefer to avoid greater compression than that. Some will perhaps see this as overly conservative.
In summary, for the smaller-bore cartridges based on the 30-06 case--the .25-06, .270 Win., .280 Rem.--Re26 is the winner for velocity at safe pressures. This is also true for pretty well all true magnum cartridges up to the .338 WM, but not beyond in bore size. And for the smaller-bore cartridges based on the .308 Win. case—the .243 Win. and 260 Rem. (but not the 7-08)—it gives top velocities. This is true also for some other .264 bore-size cases like the 6.5 Creedmoor and the larger .264 cartridges.
I should reiterate that these calculations are based entirely on QuickLoad algorithms and not actual chronographed velocities. My original purpose with this thread was to see whether empirical results with Re26, based on chronographed velocities, paralleled the QuickLoad predictions. From the earlier posts in this thread, it appears that they do. However, perhaps this has been wasted effort, as it appears that Re26 is almost impossible to obtain these days, and, given the recent disappointing announcement about the discontinuance of all Alliant powders, it may be some time before we see it again.
RJ
