Thread: Relationship Between Case Capacity and Muzzle Velocity

Originally Posted by chainsaw

based on my own experience with 280ai (REM700 action, 24in bbl 1:85 twist) I think 75 - 100 fps gain is about right for the 7mm/280 comps. The exact number (or size of gain) I've found to be more dependent on selection of powder than brass. I'm getting 2980 fps with the old 162 AMAX running N560. With 2217 it was maxing out at 2920 - 2930 fps before hitting pressure signs. I've also seen claims of 280ai driving the 160 -162 pills at well north of 3000 fps .... I guess some chronies must have a feature to report "optimistic" values.

Greetings Chainsaw,
The increase in velocity using John's rule is about 50 fps in the .280AI. Handloading data from Hodgdons gives more but once again the pressure is higher so you could get half the gain by loading the .280 to the higher pressure. Wouldn't look as cool or be as trendy though. And there we have the main attraction.
Regards Grandpamac.