A rimless cartridge has a rim the same diameter (or smaller, in a couple rare oddballs) and is “held” in the chamber between the breechface and the shoulder of the cartridge (or the forward rim of the cartridge, in the case of handgun cartridges). Examples would be the .308 Winchester, the .223 Remington, or the .45 ACP.
The .17 Remington was introduced in 1971 by Remington Arms Company for their model 700 rifles. It is based on the .223 Remington case necked down to .172 in (4.37 mm), with the shoulder moved back. It was designed exclusively as a varmint round, though it is suitable for smaller predators. There are those such as P.O. Ackley who used it on much larger game, but such use is not typical. Extremely high initial velocity (over 4000 ft/s 1200 m/s), flat trajectory and very low recoil are the .17 Remington's primary attributes. It has a maximum effective range of about 440 yards (400 m) on prairie dog-sized animals, but the small bullet's poor ballistic coefficients and sectional densities mean it is highly susceptible to crosswinds at such distances.
The 223 Remington is a rifle cartridge, originally developed in 1957 as a commercial hunting bullet for varmint hunting. The first rifle chambered for it came out in 1963. It has continued to be a popular civilian small game hunting cartridge. Though it finds occasional use on medium game, this is not recommended and is illegal in at least ten U.S. states and the United Kingdom, where the .243 Winchester or similar cartridges are the smallest bore cartridges that are legal for hunting deer. A military version, M193, with a 55-gr full metal jacket bullet was used by the United States Army in the M16 rifle. The 5.56×45mm NATO was also developed from the 223 Remington.
The .243 Winchester (6.2×52mm) is a popular sporting rifle cartridge. Developed as a versatile short action cartridge to hunt both medium game and small game alike, it "took whitetail hunting by storm" when introduced in 1955, and remains one of the most popular whitetail deer cartridges. It is also commonly used for harvesting blacktail deer, pronghorns and mule deer with heavier rounds, and is equally suited to varmint hunting with lighter rounds. The .243 is based on a necked down .308 Winchester, introduced only three years earlier. Expanding monolithic copper bullets of approximately 80 to 85 grains or traditional lead rounds of 90 to 105 grains with controlled expansion designs are best suited for hunting medium game, while lighter rounds are intended for varmints. In at least ten U.S. states and the United Kingdom, the .243 or similar cartridges are the smallest bore cartridges that are legal for hunting deer. The cartridge can be extremely accurate to 300 yards (270 m) and beyond, but may not retain enough terminal energy to reliably drop medium game at that distance. Highly experienced hunters use the .243 Winchester to routinely drop bucks up to 250 pounds (110 kg), while young and/or female hunters can be just as capable with the .243 because of its very low recoil yet high velocity. Besides hunting applications, the cartridge is popular with target and metallic silhouette shooters for those same recoil and velocity properties, with superb accuracy.The .243 Winchester has regularly made the top five of rankings for "Best Whitetail Deer Hunting Cartridges" from sources such as Field and Stream and Outdoor Life, and its widespread popularity (called the "whitetail hunter's favorite" by the Browning Arms Company and "American favorite" by American Rifleman) assures chamberings in newly manufactured offerings of not only bolt-action rifles, but also semiautomatic rifles (e.g., Browning BAR), lever action rifles (e.g., Henry Long Ranger), and pump action rifles (e.g., Remington 7600). Gun Digest estimates that (as of the end of 2018) the .243 Winchester is the second-most popular of all hunting rifle chamberings (after the long action .30-06). Commentators such as popular ammunition author Chuck Hawks have opined that the .243 Winchester (as a "6mm NATO" round) should replace the 5.56×45mm NATO (.223 Remington) for most United States Armed Forces use cases but the .243 has, as of 2021, never been used as a military cartridge.
The .270 Winchester is a rifle cartridge developed by Winchester Repeating Arms Company in 1923 and unveiled in 1925 as a chambering for their bolt-action Model 54. The cartridge is the same length as the .280 Remington, both of which are longer than the .30-06 Springfield. The .270, .280, and .30-06 were all derived from the .30-03 parent case that came from the German 8x57 Mauser case which itself was based on the earlier 7x57 Mauser case. The .270 Winchester uses a .270 inch (6.86 mm) bore diameter and a .277 inch (7.04 mm) bullet diameter. The .270 Winchester became a very popular cartridge due to the widespread praises of gunwriters like Townsend Whelen and Jack O'Connor who used the cartridge for 40 years and touted its merits in the pages of Outdoor Life. It drives an 8.4 grams (130 gr) bullet at approximately 960 m/s (3,140 ft/s), later reduced to 930 m/s (3,060 ft/s). The cartridge demonstrated high performance at the time of its introduction and was marketed as being suitable for big game shooting in the 270 to 460 metres (300 to 500 yd) range, when that was considered long range hunting. With modern bullets and optics, it is easily a 1,000 yard cartridge. Two additional bullet weights were soon introduced: a 6.5 grams (100 gr) hollow-point bullet for vermin shooting, and a 9.7 grams (150 gr) bullet for deer, elk, and moose in big-game hunting. Renowned gunsmith Harold Fredd considers the 270 to be one of the most versatile cartridges for North American hunting and has recently started promoting it for small to medium sized plains games.