7-30 Waters

The 7-30 Waters cartridge was originally a wildcat cartridge developed by author Ken Waters in 1976 to give better performance to lever-action rifle shooters than the parent .30-30 Winchester cartridge, by providing a higher velocity and flatter trajectory with a smaller, lighter bullet. By 1984, Winchester introduced a Model 94 rifle chambered for the 7-30 Waters, establishing it as a commercial cartridge. In 1986, Thompson/Center began chambering 10-inch, 14-inch and 20-inch Contender barrels for the cartridge.

Development

Why neck down a .30 cal. cartridge to 7mm? This quote from a review of the 7-08 Rem. (a .308 Win. case necked down to 7mm), provides the answer.

There are two primary reasons a 7mm recoils less than an comparably effective .30 cal. cartridge: (1) to match the 7mm's ballistic coefficient requires a significantly heavier .30 cal bullet; and (2) to drive that heavier .30 cal bullet at similar velocities (for kinetic energy and wind resistance ("time-to-target")), requires more powder. This combination of heavier bullets with heavier powder charges significantly increases the recoil of the .30 caliber.