For PP and anyone interested in muzzle velocity barrel, screw and tumbling bullets on impact.
//The reason ANY bullet can be fired accurately is due to the rifling in the barrel, spiral grooves cut inside the gun’s barrel that catch the bullet’s “skin” as it is fired which impart a spin on the bullet like a football from the hand of Brett Favre. The spinning bullet acts like a gyroscope; it doesn’t like getting pushed around. That’s why spinning bullets are accurate, and can make hits at a mile or more; their spin helps keep them flying straight and on course. Gravity affects bullet flight, of course, and wind blows them around quite a bit, but for the most part the rifling spin keeps the bullet flying straight. Canadian sniper sets world record with 2.2-mile pickoff of ISIS fighter According to Ben Franklin, the British unrifled “Brown Bess” military “rifle”, which fired a round lead ball from a smooth barrel, were so inaccurate that a British soldier would have a better chance of hitting the moon than hitting a man at 100 yards. In contrast, American Minutemen using rifles considered a man at 100 yard almost to be a chip shot. Long rifle - Wikipedia
The M-16 fired a round called the 5.56 NATO, a very small .224 caliber bullet weighing only 55 grains (about 1/8th of an OUNCE) traveling out of the barrel at over 3000 feet per second (fast!). Now as to the M-16’s bullet tumbling in flight like a saw blade, of course it didn’t. It couldn’t have; our soldiers wouldn’t have been able to hit anything fifty feet away from them if it did. But the rifling spin imparted to the small bullet was only 1 spin for every 12 inches of flight (1 in 12, for gun guys), just enough to keep the little .22 cal. bullet stable when flying through the atmosphere, but no more. When that tiny, fast moving but slow spinning bullet met additional resistance by striking a flesh and blood target, it would destabilize, and tumble end over end inside whatever it hit, creating a terrible wound. 5.56 bullet wound illustration • r/Military
In fact, the 5.56 often made a worse wound than the bigger 7.62 (.30 cal) round it replaced. The 7.62 NATO round, firing a much heavier bullet at a higher rate of spin, was so stable that it would often (not always, but often) stay stable even after it hit an enemy combatant, leaving a .30 caliber hole in and out as it flew straight through.
This sounds great for the 5.56, and often it was, but a barely stable bullet does not always penetrate barriers very well. And our enemies have a downright rude habit of firing at our soldiers from behind trees, berms, walls, etc. So the quick tumble on contact was a mixed benefit.
Varying conditions call for varying weaponry. In Viet Nam the combat ranges were relatively short, the targets were small (the average Vietnamese weighed about 120 pounds) and unarmored, and the 5.56 (once the rifles firing it were made reliable) did devastating work. In the sandbox we are fighting in now, ranges are a lot longer, targets are a lot better covered, and the 5.56 has come under some criticism. In an effort to make it better at penetration and give it added range, the 5.56 bullet has been increased in weight to 64 grains, and the rifling spin has been tightened. This has succeeded in improving the round for the most part, but it may be that the legendary lethalness of the spinning bullet is somewhat less than it used to be. //
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