I prefer flat shooting rifles. My two hunting rifles are a .25-06 and a .300WM (in part because they both use the same powders for reloading). I have been thinking about looking for a hunting rifle in-between my .25-06 and .300WM that offers lower recoil than my .300WM, is better suited for deer and bigger game than my .25-06, and still uses the same powders (since components are so hard to come by these days).
I've been intrigued by the .280AI for a few years and the 6.5 PRC seems to be cool new kid on the block, so I decided to compare them. I assumed the 6.5 would offer lower recoil and better ballistics (less drop and drift) while the .280AI would offer more energy and a bigger hole. The data agree, but the difference between the two was much smaller than I expected. They are close enough that factors beyond the ballistics would have to drive one's decision.
Here follows my comparison approach and results. I decided begin by selecting similarly constructed bullets with similar sectional densities and BCs to try to make this as close to apples/apples as possible. I settled on the 140 gr. Accubond for the 6.5 (SD = 0.287; BC = 0.589) and the 160 gr Accubond for the .280AI (SD = 0.283; BC = 0.531). I then used the average of the highest three velocities for that weight bullet from Hodgdon's online reloading data (2,970 fps for the 6.5 and 2882 for the .280AI) and ran the ballistics in Hornady's online ballistics calculator. I also plugged the relevant data (including the previously mentioned average velocity and average charge weights for those powders) into the recoil calculator at shooterscalculator.com for an 8lb rifle. Here are the results:
Velocity fps (Muzzle/500 yards): 6.5 PRC (2,970/2,113) // .280ai (2,882/2,073)
Energy ft-lbs (Muzzle/500 yards): 6.5 PRC (2,742/1,389) // .280ai (2,951/1,527)
Drop inches @ 500 yards (200 yard zero): 6.5 PRC -38.4 // .280ai -40.5
10 mph/90 degree Drift inches @ 500 yards: 6.5 PRC 17 // .280ai 16
Recoil ft-lbs: 6.5 PRC 21.06 // .280ai 22.82
Recoil fps: 6.5 PRC 13.01 // .280ai 13.55
So, my expectations were correct, but the differences are so small that they are meaningless in the real world. Here is a summary of the advantages for each metric:
Energy ft-lbs (Muzzle/500 yards): +209/+138 advantage for .280ai
Drop inches @ 500 yards: +2.1 advantage for 6.5 PRC
Drift inches @ 500 yards: +1 for .280ai (although it may be closer as the Hornady calculator rounds).
Recoil: -1.8 ft-lbs and -0.5 fps advantage for 6.5 PRC
I don't think any animal and the majority of shooters in real world situations would be able to tell the difference between these two. I was most surprised that the trajectory and wind drift were so close. I expected the 6.5 to be significantly better, but it's basically a tie. I also expected the 6.5 to offer a greater reduction in recoil. Again, it's basically a tie.
The old .280ai stands up to the cool new kid pretty darn well!
I've been intrigued by the .280AI for a few years and the 6.5 PRC seems to be cool new kid on the block, so I decided to compare them. I assumed the 6.5 would offer lower recoil and better ballistics (less drop and drift) while the .280AI would offer more energy and a bigger hole. The data agree, but the difference between the two was much smaller than I expected. They are close enough that factors beyond the ballistics would have to drive one's decision.
Here follows my comparison approach and results. I decided begin by selecting similarly constructed bullets with similar sectional densities and BCs to try to make this as close to apples/apples as possible. I settled on the 140 gr. Accubond for the 6.5 (SD = 0.287; BC = 0.589) and the 160 gr Accubond for the .280AI (SD = 0.283; BC = 0.531). I then used the average of the highest three velocities for that weight bullet from Hodgdon's online reloading data (2,970 fps for the 6.5 and 2882 for the .280AI) and ran the ballistics in Hornady's online ballistics calculator. I also plugged the relevant data (including the previously mentioned average velocity and average charge weights for those powders) into the recoil calculator at shooterscalculator.com for an 8lb rifle. Here are the results:
Velocity fps (Muzzle/500 yards): 6.5 PRC (2,970/2,113) // .280ai (2,882/2,073)
Energy ft-lbs (Muzzle/500 yards): 6.5 PRC (2,742/1,389) // .280ai (2,951/1,527)
Drop inches @ 500 yards (200 yard zero): 6.5 PRC -38.4 // .280ai -40.5
10 mph/90 degree Drift inches @ 500 yards: 6.5 PRC 17 // .280ai 16
Recoil ft-lbs: 6.5 PRC 21.06 // .280ai 22.82
Recoil fps: 6.5 PRC 13.01 // .280ai 13.55
So, my expectations were correct, but the differences are so small that they are meaningless in the real world. Here is a summary of the advantages for each metric:
Energy ft-lbs (Muzzle/500 yards): +209/+138 advantage for .280ai
Drop inches @ 500 yards: +2.1 advantage for 6.5 PRC
Drift inches @ 500 yards: +1 for .280ai (although it may be closer as the Hornady calculator rounds).
Recoil: -1.8 ft-lbs and -0.5 fps advantage for 6.5 PRC
I don't think any animal and the majority of shooters in real world situations would be able to tell the difference between these two. I was most surprised that the trajectory and wind drift were so close. I expected the 6.5 to be significantly better, but it's basically a tie. I also expected the 6.5 to offer a greater reduction in recoil. Again, it's basically a tie.
The old .280ai stands up to the cool new kid pretty darn well!