Your trying to Cartridge Category compare your 7mm bullet ( .284 ) to a 7.62mm bullet (.308 )
It doesn't work that way,.
... Examples for Accurate Ballistic Calculation comparisons ...
...... Standard Cartridge's .....
.
.308 Winchester ... 155gr ELD Match ... 2,800fps. ... B.C. 0.439
30-06 Springfield ...168gr ELD Match ... 2,950fps. ... B.C. 0.490
...... Magnum Cartridge's ......
300 Win. Mag. ... 178gr ELD-X .... 3,100fps. ... B.C. 0.545
....... Ultra Magnum Cartridge's ......
300 Rem Ultra Mag. .. 200gr ELD-X .... 3,150fps ... B.C. 0.626
These are just a few .. Cartridge Comparison Category's .. the bullet weight and speed vary for optimum performance.