Just out of curiosity, I did some QuickLoad comparisons with these two cartridges loaded with the same bullets to the same COAL and to the exact same pressures—60,000 PSI. According to several sources, the difference in total capacity (up to the case mouth) is about 5 grains, or a difference of about 7.3% (73 vs 68 gr. of water). As noted by Dan Belisle the rule of ¼ applies pretty well here (predicting a gain in velocity of about 1.8%), and this corresponds pretty closely to Leeper’s estimate of about a 60 fps. advantage for the AI at the usual velocities for each.
In my analysis with QuickLoad, I obtained results for two bullets: (1) the 160-gr. Sierra HPBT Game King and (2) the 150-gr. Nosler Partition. For each bullet, I ran three powders: (1) Alliant Re22, (2) H48331 SC and (3) Alliant Re26 (which gave by far the best velocities for both cartridges at safe pressures). In all six trials, I set the COAL to 3.33”, and set the pressure to 60,000 PSI, a fairly high pressure, but safe in both. So, a true apples-to-apples comparison,I think, as much as this can be accomplished.
The results were a little surprising, although not out of line in any way. Over all six trials, the .280 AI gave, on average, a 40 fps advantage, or a 1.36% advantage in velocity, over the .280 Rem. All velocities were in the 3000 fps range. So the QL results showed a slightly smaller velocity advantage for the AI than would be predicted by the ¼ rule, although the difference is not great. The ¼ rule would predict an average velocity gain of about 53 fps.
In any case, it seems to me that there is very little to gain in performance in going to the .280 AI over the standard .280 Rem. This is not to imply that the .280 AI is not a good cartridge; it clearly is, but just not much better than the .280 Rem. with respect to performance. The advantage, however, noted for the AI of less case-stretching (and less frequent trimming) is real. I don’t have either, but one small advantage, I think, for the standard cartridge would be in resale value of the rifle, as the standard 280 Rem. has been around and readily available for far longer commercially than the AI. There are at least seven different brands of ammunition available (plus some custom brands) for the 280 Rem., and at least six brands of unfired brass, both outnumbering the same for the AI.
In my analysis with QuickLoad, I obtained results for two bullets: (1) the 160-gr. Sierra HPBT Game King and (2) the 150-gr. Nosler Partition. For each bullet, I ran three powders: (1) Alliant Re22, (2) H48331 SC and (3) Alliant Re26 (which gave by far the best velocities for both cartridges at safe pressures). In all six trials, I set the COAL to 3.33”, and set the pressure to 60,000 PSI, a fairly high pressure, but safe in both. So, a true apples-to-apples comparison,I think, as much as this can be accomplished.
The results were a little surprising, although not out of line in any way. Over all six trials, the .280 AI gave, on average, a 40 fps advantage, or a 1.36% advantage in velocity, over the .280 Rem. All velocities were in the 3000 fps range. So the QL results showed a slightly smaller velocity advantage for the AI than would be predicted by the ¼ rule, although the difference is not great. The ¼ rule would predict an average velocity gain of about 53 fps.
In any case, it seems to me that there is very little to gain in performance in going to the .280 AI over the standard .280 Rem. This is not to imply that the .280 AI is not a good cartridge; it clearly is, but just not much better than the .280 Rem. with respect to performance. The advantage, however, noted for the AI of less case-stretching (and less frequent trimming) is real. I don’t have either, but one small advantage, I think, for the standard cartridge would be in resale value of the rifle, as the standard 280 Rem. has been around and readily available for far longer commercially than the AI. There are at least seven different brands of ammunition available (plus some custom brands) for the 280 Rem., and at least six brands of unfired brass, both outnumbering the same for the AI.
