The 6mm PPC-USA and 6mm BR Remington
By Chuck Hawks
These two attenuated 6mm (.243) cartridges were specifically designed for the rather esoteric world of Sporter Class bench rest shooting, which requires a caliber of at least .24/6mm coupled with extreme accuracy. The 6mm PPC is quite popular in this arena, and the 6mm BR Remington is that company's attempt to cut into the market.
Their ballistics are very similar. And, indeed, the two cartridges even look very similar. 60-70 grain match bullets are typically used for competition in single shot bench rest rifles. Their greater resistance to crosswinds gives the 6mm bullets an advantage over the lighter bullets used in the .22 BR cartridges.
These cartridges were designed specifically for use in bolt action single shot rifles. Neither cartridge is well suited for use in repeating rifles due to their very short, sharp shouldered cases, which make for serious feeding problems. It is often impossible to get these cartridges to feed from the magazine of even a custom made and tuned bolt action rifle. They were designed for, and should be restricted to use in, single shot rifles.
Note that bench rest rifle barrels for both calibers usually come with a 1-14 inch twist and will not stabilize bullets heavier than 70 grains. Also note that custom made bench rest rifles usually require that case necks be outside turned to precisely match their very tight chamber dimension.
As one would expect, both cartridges deliver outstanding accuracy, low recoil, and relatively low noise, which makes them very suitable not only for bench rest target shooting. Neither can equal the .250 Savage, .243 Winchester or 6mm Remington as varmint or general purpose hunting cartridges.
The 6mm PPC was designed in 1975 by Ferris Pindell and Louis Palmisano for bench rest shooting. PPC stands for Pindell-Palmisano Cartridge. It was based on a necked-up and fireformed .220 Russian case (another target round).
The 6mm PPC is a very stubby round, with a case only 1.503 inch long and a rim diameter of .445 inch. The shoulder angle is 30 degrees. The case uses small rifle primers. There is no standard cartridge overall length for the 6mm PPC, which uses standard .243 inch diameter bullets.
Norma of Sweden and Sako of Finland supply 6mm PPC brass for handloaders, and Sako chambers rifles for the cartridge. The letters "USA" were added to the designation "6mm PPC" at the request of Louis Palmisano when Sako standardized the cartridge in 1985.
Sako offers a factory load using a 70 grain HPBT Match bullet at a MV of 3200 fps and ME of 1481 ft. lbs. At 200 yards the Sako figures are 2407 fps and 892 ft. lbs. Sako ballistic tables show the following trajectory for this load: +1.5 inches at 100 yards, 0 at 200 yards, -7.2 inches at 300 yards.
This Sako factory load is typical of bench rest loads for the 6mm PPC. Handloaders can duplicate the ballistics of either using similar HPBT match bullets at MV's in the 3100-3200 fps range.
Most reloading manuals have loading data for the 6mm PPC. The Nosler Reloading Guide #5 shows that their 55 grain Ballistic Tip varmint bullet can be driven to MV of 3348 fps with a maximum load of 28.5 grains of H322 powder. The 70 grain Ballistic Tip varmint bullet in front of 25.5 grains of H322 delivered a MV of 3088 fps. Nosler technicians found H322 to be the most accurate powder with both bullet weights; test barrel length was 22 inches. The Nosler trajectory tables show the following for a 55 grain bullet at 3300 fps: +1.3 inches at 100 yards, 0 at 200 yards, and -6.4 inches at 300 yards.
The following information for heavier bullets is taken from the Speer Reloading Manual #13. The Speer test rifle had a 1-12 inch twist barrel. The 85 grain Speer BT spitzer bullet can be driven to a MV of 2703 fps with 25.5 grains of H335, or 3156 fps with 29.5 grains of the same powder. The 90 grain Speer Hot-Cor spitzer bullet can be driven to a MV of 2601 fps with 25.0 grains or 3031 fps with 29.0 grains of H335. The Speer 90 grain Hot-Cor spitzer bullet has a trajectory like this at a MV of 2900 fps: +1.9 inches at 100 yards, 0 at 200 yards, -7.7 inches at 300 yards.
6mm BR Remington
The 6mm Bench Rest Remington was introduced by that company in 1978, chambered in their 40X target rifle. At first it was strictly a cartridge for reloaders, and cases had to be formed from Remington's Universal Bench Rest Brass. But at some point Big Green began offering 6mm BR factory loaded ammunition. Remington and Norma currently offer brass for handloading.
The 6mm BR is based on a very short, fat, thoroughly modern case designed by Remington's Jim Stekl. The case is 1.56 inches long with a 30 degree shoulder and a standard .473" rim diameter. The latter is important, as it mates with standard bolt faces, unlike the 6mm PPC and most other bench rest cartridges. This makes it easier to build a custom bench rest rifle. As a factory standardized cartridge, the overall length of the 6mm BR cartridge has been set at 2.2 inches. Like most 6mm target cartridges it uses small rifle primers and standard .243 inch bullets.Remington's factory load for the 6mm BR drove a 100 grain bullet at a MV of 2550 fps with 1444 ft. lbs. of ME. At 200 yards the figures were 2083 fps and 963 ft. lbs. The trajectory of that load looked like this: +2.5 inches at 100 yards, -0.6 inch at 200 yards, and -11.8 inches at 300 yards. I am not sure about the intended purpose of this load, which I believe has since been discontinued. It would have required a rifle barrel with a 1-10 inch twist to stabilize the 100 grain spitzer bullet.
Handloaders using 6mm BR rifles for bench rest competition can load 60-70 grain HPBT match bullets at MV's in the 3100-3200 fps range with great accuracy. Such loads are directly comparable to similar match loads for the 6mm PPC.
Reloading data for the 6mm BR cartridge can be found in the Hodgdon and Nosler Reloading Manuals. The following data for varmint bullets is taken from the Nosler Reloading Guide #5.
The 55 grain Nosler Ballistic Tip varmint bullet showed a MV of 3112 fps in front of 27.0 grains of RL7 powder and 3720 fps in front of 31.0 grains of RL7. RL7 was the most accurate powder tested with this bullet. With the 70 grain Ballistic Tip bullet 28.0 grains of H4895 powder gave a MV of 2919 fps, and 32.0 grains of the same powder gave a MV of 3321 fps. H4895 was the most accurate powder tested with this bullet. The Nosler trajectory tables show the following for a 70 grain bullet at 3300 fps: +1.2 inches at 100 yards, 0 at 200 yards, and -6.1 inches at 300 yards.
Berger and Sierra, in particular, make appropriate 60-70 grain match bullets for use in 6mm target rifles. These are ideal for competition use in 6mm PPC-USA and 6mm BR Remington bench rest rifles. These two calibers have been used to set literally hundreds of bench rest records, about 90% of them with the 6mm PPC.
In addition, as we have seen, varmint bullets weighing up to 70 grains can be used in rifles with normal 1-14 inch twist barrels. It should be reiterated that these short, fat cartridges with their sharp shoulder angles can cause feeding problems in repeating rifles, which makes them unsuitable for use as general purpose hunting cartridges. But, in single shot bench rest rifles, they are hard to beat.
Copyright 2003, 2012 by Chuck Hawks. All rights reserved.