Home Forums Hunting & Shooting Ask The Gunwriters Case weight vs Capacity

There are a number of reasons why capacities vary, but they can change lot to lot. Sometimes, companies have their brass manufactured by someone else. There have been changes to ammunition/component specifications as well, although this last thing doesn't happen often.

Web and wall thickness also play a role. When they draw the cups while forming the cases, small variances will occur. A few grains isn't much. You would have to speak with an engineer to find out how much of a swing is brought about by 0.001 variance in wall or web thickness.