The seven-millimeters form a ladder. Each rung up adds velocity, and each costs something in recoil, powder and barrel life. Knowing the rungs makes it easier to pick the cartridge you will actually enjoy shooting.

The bottom rungs: mild and moderate

The 6.8 SPC is the smallest rung, an AR-15 round for modest ranges, and its loads are at 6.8 spc ammo for sale. The 7mm-08, a .308 case necked to 7mm, adds a flat-shooting short-action option with gentle recoil, and its polymer-tip loads are at 7mm-08 polymer tip ammo.

Europe's rimmed 7x57R, the break-action version of the 7x57 Mauser, sits here too. RWS, the German maker long associated with European hunting cartridges, loads it, and those loads are at rws 7x57r ammo.

The short magnums

The 6.8 Western, a short magnum from Winchester and Browning, shoots a .277-inch bullet at magnum speeds, and its loads are at 6.8 western ammo. The 7mm PRC does a similar job with a 7mm bullet, and anyone who wants to buy 7mm prc ammo will be buying a short-action magnum.

The 7mm Backcountry takes its name from mountain hunting, and its heavy 195-grain loads are at 7mm backcountry 195 grain ammo.

The belted magnums

Belted magnums are the classic middle of the ladder. The 7mm Remington Magnum, whose loads from Nosler are at nosler 7mm rem mag ammo, is the benchmark. Weatherby's 7mm Magnum, whose 160-grain loads are at 7mm weatherby magnum 160 grain ammo, is a rival of similar power from the company that popularized belted magnums.

The 7mm STW, short for Shooting Times Westerner, is a hotter belted cartridge that began as a wildcat in the late 1980s and was later standardized by Remington. Its loads are at 7mm stw ammo.

The top rung

The 7mm Remington Ultra Mag sits at the top of the ladder with the biggest case of the group. Polymer-tip loads like those at 7mm rum polymer tip ammo are built to make the most of its speed, and the trade-off is recoil and barrel wear that shooters should expect.

Magnum cartridges demand a rifle built for them. Match the chambering to the box, and confirm current stock and state shipping restrictions before ordering.