If there is a "fountain of youth" in ballistics, it is the ability to make little bullets behave like big bullets. It is not a new concept, rather an ancient ballisticians' dream. From the .75 caliber "Brown Bess" and the .69 caliber Charleville, popular calibers have diminished to .223 for the military and .17 for civilians.
When you reduce a bullet to 1/3 of its original weight, you are left with 1/3 of the original kinetic energy. To maintain the same kinetic energy, the new bullet would need about 73 percent more speed. But, what if you could make the little bullet twice as efficient as the big bullet? Then it might only need 25 to 30 percent more speed to equal the big bullet's performance. If this sounds like the .45-70 v. .30-40, .308 v. .223 or the .223 v. .17, then you're right. That's how those changes came to pass.
Prior to WWII, the U.S. Army convened pig and goat boards to evaluate a new caliber for the soon to be adopted semiauto rifle. As we all know the M1 Garand was produced in .30-06, but .25 and .276 rifles were also tested. The tests concluded that within 500 yards the .25 caliber bullet starting at 2550 fps was more effective than the .30-06 bullet starting at 2900 fps. How could this be?
The tests were not flawed, rather the .25 bullet was designed to take advantage the yaw that occurs when a bullet enters tissue at a high velocity. Of course .30 caliber bullets can be designed the same way. The smaller caliber offers reduced fatigue from firing, plus lighter weight.
When a stable .30 bullet strikes an enemy soldier, it may only use 10 or 15 percent of its kinetic energy creating the wound. The secret to making little bullets behave like big bullets is to create a high drag on impact. Yawing both increases the area pressing against the tissue and the bluntness of the bullet. Expanding, yawing and other high drag bullets may be able to use 50-70 percent of their kinetic energy for wounding. Expanding and fragmenting bullets have been unacceptable to many nations since The Hague Convention of 1902. This leaves yawing as a wound mechanism in military bullets.
However, we've all know about yawing bullets for some time. So, how do they work? They shift the bullet's center of gravity further rearward than it might ordinarily be. The British used an aluminum nose in their Mk VII .303's, the Russian 5.45x39.5mm and Chinese 5.8mm use air spaces, but there is a simpler way...make the bullet longer. Accuracy is maintained with a tighter twist. An enemy soldier will be 900-1000 times denser than air, so the twist will not stop the bullet from yawing. The twist for a 55 grain .223 would have to be changed from 1 turn in 12 inches to about 1 turn in 3/8 inch to remain stable in tissue! At high velocities, a sharply yawing bullet may fragment, expending 100 percent of its energy wounding. That's how the little bullets do it.
When you reduce a bullet to 1/3 of its original weight, you are left with 1/3 of the original kinetic energy. To maintain the same kinetic energy, the new bullet would need about 73 percent more speed. But, what if you could make the little bullet twice as efficient as the big bullet? Then it might only need 25 to 30 percent more speed to equal the big bullet's performance. If this sounds like the .45-70 v. .30-40, .308 v. .223 or the .223 v. .17, then you're right. That's how those changes came to pass.
Prior to WWII, the U.S. Army convened pig and goat boards to evaluate a new caliber for the soon to be adopted semiauto rifle. As we all know the M1 Garand was produced in .30-06, but .25 and .276 rifles were also tested. The tests concluded that within 500 yards the .25 caliber bullet starting at 2550 fps was more effective than the .30-06 bullet starting at 2900 fps. How could this be?
The tests were not flawed, rather the .25 bullet was designed to take advantage the yaw that occurs when a bullet enters tissue at a high velocity. Of course .30 caliber bullets can be designed the same way. The smaller caliber offers reduced fatigue from firing, plus lighter weight.
When a stable .30 bullet strikes an enemy soldier, it may only use 10 or 15 percent of its kinetic energy creating the wound. The secret to making little bullets behave like big bullets is to create a high drag on impact. Yawing both increases the area pressing against the tissue and the bluntness of the bullet. Expanding, yawing and other high drag bullets may be able to use 50-70 percent of their kinetic energy for wounding. Expanding and fragmenting bullets have been unacceptable to many nations since The Hague Convention of 1902. This leaves yawing as a wound mechanism in military bullets.
However, we've all know about yawing bullets for some time. So, how do they work? They shift the bullet's center of gravity further rearward than it might ordinarily be. The British used an aluminum nose in their Mk VII .303's, the Russian 5.45x39.5mm and Chinese 5.8mm use air spaces, but there is a simpler way...make the bullet longer. Accuracy is maintained with a tighter twist. An enemy soldier will be 900-1000 times denser than air, so the twist will not stop the bullet from yawing. The twist for a 55 grain .223 would have to be changed from 1 turn in 12 inches to about 1 turn in 3/8 inch to remain stable in tissue! At high velocities, a sharply yawing bullet may fragment, expending 100 percent of its energy wounding. That's how the little bullets do it.
