User:Ruppertmd

The weapon commonly referred to as the Thompson Submachine Gun was chambered for several other cartridges during its initial development in 5 year period before and after Colt's initial run of 15,000 weapons in 1921. The most powerful being the .351 Winchester Autoloading round, several others were also attempted as the strength and weight of the arm made it capable of handling pressures higher than that of the 45ACP round used in the 1911 autoloading pistol. Among these were the 45 Remington-Thompson round, also known as the 45 Remington Military. Basically intended for use in a variant fitted with a longer barrel, bipod, and bayonet attaching mechanism, it used the same external case dimensions as the 45 ACP except the case length being 1/10 inch longer to prevent the round being chambered in the 1911/1911A1 pistol. As these headspace on the rim mouth it would not allow the pistol slide to close. Ballistically the difference was a marked increase in velocity, the 45ACP throwing a 230 grain ball round at around 850 feet/second the 45 Remington Military or 45 Remington Thompson launched the same 230 grain ball projectile at around 1600 feet/second. The degree of increased potency is obvious but quantification is difficult depending on whether the observer gauges potency by kinetic energy (mass x velocity x velocity/mass x velocity squared) or momentum (mass x velocity). This subject is a controversy to this day unresolved within the shooting community. A more clear example is a comparison of the 9mm luger round versus the 45 ACP round. The 9mm has higher kinetic energy while the 45 has higher momentum. This observers anecdotal studies indicate that the older more experienced law enforcement, military, and hunting community lean toward momentum while the younger civilian and target community seem more impressed with kinetic energy focusing on projectile design to maximize dispersal of energy within the target and avoid excess penetration. Interestingly this concept has recently been reintroduced as the 460 Rowland cartridge along with the attendant conversion components to allow its use in the 1911 platform. The 460 Rowland setup offered by Clarks Custom Guns lists maximum loads using the 230 grain projectile at 1300 feet/second with an observed pressure limit of 40,000 CUP. While these cartridges externally differ only in length, the 45 Remington Military being a tenth inch longer and the 460 Rowland being a sixteenth longer, internally the old and new higher power shells internally are structured to be much stronger with thicker brass, webbing etc. (The 30-06, .308, and 45 ACP and those above all share similar base dimensions.) Interestingly the US military's initial rejection of this weapon was due to the excessive cyclic rate due to bolt design of the initial 500 arms produced and not the limited power of the 45ACP. An increase in actuator size and weight subsequently reduced the cyclic rate from 1800/minute to the more efficient 1000-1200/minute rate. The WW2 adaptations M1 and M1A1 reverted to a simple blowback mechanism and dropped the cyclic rate further to 600-800 rounds per minute. References - Catalog for the Thompson Machine Gun Exhibit at the Ruger Firearms Museum.