First, lets lay out the publicly available data & definitions:
Muzzle energy is the kinetic energy of a bullet as it is expelled from the muzzle of a firearm. It is often used as a rough indication of the destructive potential of a given firearm or load. The heavier the bullet and especially the faster it moves, the higher its muzzle energy and the more damage it will do.
- Thompson Flintlock: 28 inch barrel, 140 grains 2F powder, 485 grain .490 conical bullet, average velocity of1345 ft/s, giving 1948 ft-lbs impact energy.
Type of gun of the Second Amendment Era.
The 9×19mm Parabellum is a firearms cartridge that was designed by Georg Luger and introduced in 1902 by the German weapons manufacturer Deutsche Waffen und Munitionsfabriken (DWM) (German Weapons and Munitions Factory) for their Luger semi-automatic pistol.
Under STANAG 4090, it is a standard cartridge for NATO forces as well as many non-NATO countries.
Average of 405 ft-lbs impact energy with 4.7″ barrel.
The .22 Long Rifle (metric designation: 5.6×15mmR) cartridge is a long-established variety of .22 caliber rimfire ammunition, and in terms of units sold is still by far the most common ammunition in the world today.
The cartridge is often referred to simply as .22 LR (“twenty-two-/ɛl/-/ɑːr/”) and various rifles, pistols, revolvers, submachine guns and even some smoothbore shotguns (No. 1 bore) have been manufactured in this caliber.
Average of 154 ft-lbs impact energy with 18.5″ barrel.
The 5.56×45mm NATO (official NATO nomenclature 5.56 NATO) is a rimless bottlenecked intermediate cartridge family developed in Belgium by FN Herstal. It consists of the SS109, SS110, and SS111 cartridges. Under STANAG 4172, it is a standard cartridge for NATO forces as well as many non-NATO countries.
It is derived from, but is not identical to, the .223 Remington cartridge.
Average of 1784 ft-lbs impact energy with 20.0″ barrel.
The 7.62×51mm NATO (official NATO nomenclature 7.62 NATO) is a rimless bottlenecked rifle cartridge developed in the 1950s as a standard for small arms among NATO countries. It should not be confused with the similarly named Russian 7.62×54mmR cartridge, a slightly longer rimmed cartridge.
Average of 2511 ft-lbs impact energy with 24.0″ barrel.