6 mm PPC

The 6mm PPC (Palmisano & Pindel Cartridge), or 6 PPC as it is more often called, is a centerfire rifle cartridge used almost exclusively for benchrest shooting. At distances out to 300 yards, it is one of the most accurate cartridges available. This cartridge's accuracy is produced by a combination of its stout posture, being only 1.23 in long, and aggressive shoulder angle of 30 degrees compared to a 30-06's 17 degrees.

Background
The cartridge is a necked-up version of the .22 PPC which is in turn based on a .220 Russian. The standard bullet diameter for 6 mm caliber cartridges is .243 in, the same diameter used in the .243 Winchester and 6mm Remington cartridges. To obtain maximum accuracy, bullet weight and form are matched to the rifling twist rate of the barrel. Typically, 68 gr bullets are used in barrels with twist rates of 1:13 (one twist for every 13" in the barrel), while 1:15 barrels can accommodate lighter 58 or accurately. The cartridge developed enough acceptance that rifles chambered for it are available commercially.

Handloading
The parent cartridge for the 6PPC is the .220 Russian, which in turn derives from the 7.62×39mm. Brass can either be purchased, or formed from .220 Russian brass (7.62 x 39 mm can also be used, but .220 Russian brass is usually higher quality and thickness, since it is designed to operate at higher pressures). The .223 inch (5.56 mm) neck of the .220 Russian is expanded to .243 inches (6 mm) by running the case through a full length sizing die for 6mm PPC. Next the case is trimmed, loaded, and fire formed by loading and firing the round through a 6mm PPC rifle. Recently, Lapua, Norma and SAKO have begun making 6mm PPC brass.

As with other cartridges used in competition, precise handloading, a good rifle, and lots of practice make it possible to shoot very small consistent groups, with 5 or 10-shot groups with center-to-center measures of under 0.200 in at 200 yards.

Other developments
As with many competition rounds, variations develop and the PPC family of cartridges has served as the foundation for many. In the native 22 and 6mm calibers, there are numerous improved versions both with a shorter body to reduce powder capacity and longer body to increase powder capacity.

In 1998 Arne Brennan conducted a theoretical study of calibers and cartridge cases and expanded the PPC family with the 6.5 PPC for the AR15 rifle platform. As time evolved, the 6.5 PPC evolved into an improved case version like had been done for years with the 22 and 6 PPC. An improved 6.5 PPC variation branded the 6.5 Grendel was marketed by Alexander Arms LLC. Others are the 6.5 CSS marketed by CompetitionShooting.com, the 6.5 PPCX developed by Arne Brennan and optimized for 100-108 grain 6.5mm bullets, and the 6.5 BPC developed by Jim Borden and Dr. Louis Palmisano and optimized for 81-88 grain flat base bullets. Brass for these improved versions of the 6.5 PPC cartridge is made by Lapua and Hornady.

In 2007, Mark Walker created the .30 Walker - a .30 caliber version of the improved PPC optimized for use with 110-118 grain flat base 30 caliber bullets. The .30 Walker was created for benchrest score shooting and has yielded impressive results with performance close to the .30 BR.

In January 2010, Les Baer Custom discontinued offering the Alexander Arms 6.5 Grendel which is a trademarked brand and required an insurance commitment until Alexander Arms released its trademark in 2011, and announced the release of the .264 LBC-AR with brass manufactured by Hornady and ammunition loaded by Black Hills Ammunition. The .264 LBC-AR chamber is designed with a .295 neck like the 6.5 CSS and uses a 1 degree throat design like the 6.5 PPCX.