I've posted a thread about this before, but I've cleaned up the graph and table so I though I would post it again for those who missed it the last time.... The Ballistics Coefficient of a bullet is calculated by the Sectional Density divided by a "Form Factor".... For most bullets it is very complex, but for a sphere it is 1.55.... Therefore, all we need to know is the caliber to calculate the BC.... Here is a graph showing what happens to the BC as you increase the caliber....



And here is the same information in a table....



The weight of a roundball is proportional to the cube of the diameter.... The Sectional Density is the weight (in lbs.) divided by the bore squared.... Therefore the SD is directly proportional to the caliber.... and the BC is directly proportional to the caliber as well.... If you double the bore, you can expect to double the BC.... When you look at the value of the BCs in the table, you will note that they are actually very close to what we get with a good quality, round nosed, diablo pellet such as the JSB Exact series.... 0.024 in .177 cal, 0.030 in .22 cal, and 0.035 in .25 cal.... From this we might expect that the new Big Bore Exacts in .30 cal and 9mm (.357) will have BCs of approximately 0.043 and 0.049 respectively....

Just some food for thought.... and something to explain why the larger calibers tend to buck the wind much better....

Bob