A Small Clean Hole

Wednesday, July 14th, 2010

Concerned soldiers in the modern US Army have complained that the M4 carbine is less effective than it should be at 500 meters. That is, at long ranges, shot from a short barrel, the glorified .22 leaves a tiny hole. (At closer ranges, or from a longer barrel, it shatters bone.)

A century ago, Theodore Roosevelt was saying the same thing about the new 7 mm Mauser rifle the Spaniards were using — it left a small clean hole:

Thomas Isbell, a half-breed Cherokee in the squad under Hamilton Fish, was among the first to shoot and be shot at. He was wounded no less than seven times. The first wound was received by him two minutes after he had fired his first shot, the bullet going through his neck. The second hit him in the left thumb. The third struck near his right hip, passing entirely through the body. The fourth bullet (which was apparently from a Remington and not from a Mauser) went into his neck and lodged against the bone, being afterward cut out. The fifth bullet again hit his left hand. The sixth scraped his head and the seventh his neck. He did not receive all of the wounds at the same time, over half an hour elapsing between the first and the last. Up to receiving the last wound he had declined to leave the firing-line, but by that time he had lost so much blood that he had to be sent to the rear. The man’s wiry toughness was as notable as his courage.
The Mauser bullets themselves made a small clean hole, with the result that the wound healed in a most astonishing manner. One or two of our men who were shot in the head had the skull blown open, but elsewhere the wounds from the minute steel-coated bullet, with its very high velocity, were certainly nothing like as serious as those made by the old large-calibre, low-power rifle. If a man was shot through the heart, spine, or brain he was, of course, killed instantly; but very few of the wounded died — even under the appalling conditions which prevailed, owing to the lack of attendance and supplies in the field-hospitals with the army.

A typical Mauser 7 mm bullet weighs 162 grains (10.5 g) and leaves the muzzle at 2,600 feet per second (800 m/s), with 2,480 foot-pounds (3,360 J) of energy.

A 5.56 mm bullet weighs just 62 grains (4 g) but leaves the muzzle (of an M16) at 3,100 feet per second (940 m/s) — for 1,303 foot-pounds (1,767 J) of energy. And the tiny bullet loses energy quickly.

The Mauser 7 mm could make its characteristic small clean hole in a large muddy beast, too:

The ballistics of the 7x57mm became popular with deer and plains game hunters. The relatively flat trajectory and manageable recoil ensured its place as a sportsman’s cartridge. The 7x57mm can offer very good penetrating ability due to a fast twist rate that enables it to fire long, heavy bullets with a high sectional density.

This made it popular in Africa, where it was used on animals up to and including elephants, for which it was particularly favored by noted ivory hunter W. D. M. Bell, who shot 1,011 elephants using a 7x57mm rifle, when most ivory hunters were using larger-caliber rifles. Bell selected the cartridge for moderate recoil, and used 11-gram military full metal jacket bullets for reliable penetration. Bell sectioned an elephant skull to determine the size and location of the brain, and used careful aim to ensure bullet placement in the brain.

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