Current Rifle Cartridges
                    7-30 Waters, or 7mm by 30/30 Wildcat
The 7-30 Waters was designed by Ken Waters,
who was a  writer of reloading articles for
Shooting Times in the 1960s.  
Ken designed the caliber in 1976 as a wildcat,
reforming the 30-30 Winchester by extending
the shoulder and necking down the mouth of
the case to accept 7mm diameter projectiles.
This produced a faster velocity and fatter
trajectory for the lever-action rifles of the day.

U.S. Repeating Arms Company (the producers
of Winchester rifles at the time) and Federal
Cartridge Company experimented with the
cartridge in 1982 by changing the shape of the
case slightly and loading a 120 grain projectile.  
The cartridge was introduced later that year.
Picture on above Right of two cartridges fro size comparson:  
Right is 30-30 Winchester, Left is 7-30 Waters