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.
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.
Anything a 7mm can do, a .30 caliber of comparable sectional density and ballistic coefficient can also do. The catch is, in order to send a .30-caliber slug over a trajectory as flat as that 7mm bullet, about 20 percent more recoil is going to be generated. . . . [A bullet in] 7mm produces clearly superior downrange performance in terms of delivered energy and trajectory at any given recoil level [compared to a bullet in .30 caliber].
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.
The .30-30 Winchester is typically limited to short ranges, primarily because of the relatively small case capacity and the 150-grain and 170-grain bullet weights. To compensate for this, Waters necked the cartridge down to use a 7mm bullet (.284 inches), rather than the original .308 caliber (7.62 mm) bullet. Because it was designed to function in lever-action rifles, the 7-30 maintained the same low working pressure, yet Waters' original design fired a lighter bullet (139 grains) at a higher velocity (2600 f/s). A typical .30-30 factory load fires a 150-grain bullet at 2390 f/s, while the current 7-30 factory load fires a 120-grain bullet at 2700 f/s. Muzzle energy is just over 1900 ft-lbs for both of these loads, but the lighter weight 7mm bullet has a higher velocity and flatter trajectory.
Lever-action rifles with tubular magazines can only safely use spitzer bullets as the first cartridge in the chamber with only flat-pointed bullets in the magazine, or if the rifle is used as a 2-shot (1 cartridge in the chamber and only 1 in the magazine).
Handloaders for single-shot 7-30 Waters rifles or pistols are not limited to flat-nosed bullets and thus have a wide range manufacturers and weights of 7mm pointed bullets from which to choose.
Federal Cartridge offers manufactured 7-30 Waters cartridges—the Federal Premium Vital-Shok firing a 120-grain (7.78 g) Sierra GameKing boat-tail soft-point flat-nose bullet at 2700 fps with 1940 ft-lbs of energy. It has a sectional density of 0.213
Hornady Manufacturing Company does not offer 7-30 Waters LEVERevolution ammunition which would allow the safe use of pointed, ballistically efficient spitzer bullets in tubular magazines.
Speer Bullets offers a 130 gr (8.42 gr), copper-jacketed soft-point flat-nosed bullet for use in lever-action rifles. It has a sectional density of 0.23 and a ballistic coefficient of 0.257
Hornady Manufacturing Company does not offer either FTX or MonoFlex bullets in 7mm/.284" caliber. These would allow the safe use of pointed, ballistically efficient spitzer bullets in tubular magazines.
[T]he 7-30 Waters cartridge, with its flatter trajectory and higher velocity, have made [the Winchester Model 94] what many consider to be an ideal mountain rifle: lightweight, but capable of reaching out for the longer shots.
By 1982, Waters had perfected his new cartridge, firing a 139-grain flat-point bullet at a muzzle velocity of 2600 f/s from a lever-action rifle with a 24" barrel. By 1983, he had managed to attract the attention of Winchester, which led to the introduction of the Model 94 angle eject 20" barreled carbine and Model 94XTR angle eject 24" barreled rifle in the new caliber in 1984. After 13 years, production ceased in 1997.
Thompson Center Arms' single-shot Contender and Encore rifles are both offered in 7-30 Waters in either stainless steel or blued steel through their custom shop.
Thompson Center Arms began to chamber the 7-30 Waters in their Contender single shot pistol starting in 1986. Factory loads are capable of velocities of 2400 f/s from the 14" pistol barrel, making the 7-30 Waters one of the fastest commercial rounds available for the pistol. In addition, the single shot Contender and Encore pistols can safely use pointed bullets, which allows the handloader to gain additional retained velocity at long ranges for uses such as handgun hunting and metallic silhouette shooting.
Paco Kelly, of leverguns.com:
I like the model 94 Winchesters....and the 7 Waters fits the standard 94 action very well. It is exactly what it was designed for...a light, handy, and fairly powerful round and rifle for deer and black bear.
Bullets in the 110- to 120-grain range are suitable for small game and varmints (handloads with 110s can nearly achieve 3000 ft/s); 120- to 154-grain range for deer; and 154 to 168 gr range are adequate for larger game at closer ranges. "The 7-30 Waters has proven its capabilities in the field on big game weighing up to 300 pounds at woods ranges. As this is written, two bullets of flat nose form are available to handloaders for use in rifles with tubular magazines. For whitetails, the 120-grain Nosler is an excellent performer, but when greater penetration is needed for Mule Deer and Black Bear, the 139-grain Hornady is a better choice." Nosler and Hornady no longer offer flat nose bullets in 7mm.
Best performance is had with the rifle barrel; with the shorter carbine barrels the .30-30 is a better choice. With the long barrel, however, the 7-30 provides flatter trajectory, and a longer effective range, as well as reduced recoil from the lighter bullets. Despite the advantages, the 7-30 still lags far behind the venerable .30-30 in popularity, however.
Where the 7-30 has gained a strong foothold is in handguns. In the field of handgun metallic silhouette shooting, a suitably loaded 7-30 Waters provides performance equal to other 7mm wildcats, such as the 7mm International Rimmed, but without the work of forming cases. It also adds the bonus of being able to shoot commercial ammunition, with some performance loss.