.223 Remington (Single-Shot Pistol) using Sierra bullets
Date: Dec 27 2019
Development for the .223 Remington began in 1957, but it was not introduced commercially until January 1964, or about a month prior to the official U.S. military adoption of a nearly identical round known as “Cartridge, 5.56 Ball, M193.” The case was based on the .222 Remington but was lengthened to increase powder capacity and velocity. It is accurate, efficient and provides mild recoil, muzzle report and long barrel life. In the past 50-plus years since its introduction, the .223 has easily become the most popular and widely used varmint cartridge in the U.S. and many foreign countries.
In addition to being offered in a variety of rifles, the .223 Remington has also been chambered in single-shot pistols such as the Thompson/Center Encore, which was used to develop the accompanying data.
There has been considerable editorial comment suggesting that the 5.56 NATO case has less capacity than the commercial .223 Remington case, and therefore loads must be reduced accordingly. This is simply not true. After weighing more than 10 different lot numbers of 5.56 cases, each from a different manufacturer, their water capacities were checked. They typically weighed between 90.5 grains and 92.5 grains and held on average around 30.06 grains of water (measured level with the case mouth). In checking commercial cases from Federal, Hornady, Nosler, Remington and Winchester, their weights varied from 89.5 to just under 95.0 grains. Short military cases, on average had less weight and water capacity variance than commercial cases. Nonetheless, their average water capacity was almost exactly the same as the combined the average of the above mentioned commercial cases.
To help obtain top accuracy and the least variation in capacity, neck thickness, tension, etc., it is suggested to develop loads in cases that are of one make and preferably of the same lot number. To develop the accompanying data, Hornady cases were used, which were of high quality and uniform.
In spite of the comparatively short, 15-inch Encore barrel, 50- grain Sierra bullets still reached over 2,900 fps with select powders, including IMR-4198, Accurate 2015 and 2230, and Winchester 748. Virtually every powder used produced respectable accuracy; however, Hodgdon H-322, Benchmark, Varget, Ramshot TAC and IMR-4198 proved to be top choices. It is also notable that H-322 and Accurate 2015 produced comparatively mild muzzle report an attractive feature when fired from a short pistol barrel or when shooting a high volume of shots at prairie dogs.