The experimental rifle that almost changed World War II
In 1928, the Army asked itself how it could make its rifles, and therefore its riflemen, more lethal in case all those building tensions in Europe and Asia eventually boiled over and triggered a new world war. After years of study and design, they came up with a rifle design that some leaders thought would be capable of tipping battles, but it never saw combat.
It started in 1928 when the Army created a "Caliber Board" to determine what the most lethal size would be for a rifle round. Their eventual conclusion would be familiar to anyone who carried an M16 or M4. While .30-caliber and larger rounds were great for hunting animals, they passed too quickly and easily through humans. The board decided that a smaller round, preferably .276 inches or smaller, would be best.
This decision was no surprise to John Douglas Pedersen, a well-known weapon designer with an experimental rifle chambered for .276-caliber that featured a delayed-blowback mechanism and a 10-round clip.
This allowed the weapon to fire reliably, and it allowed infantrymen and cavalrymen to maintain a high rate of fire. A demonstration of the weapon pleased senior Army leaders, and they asked when they could take prototypes to the field for testing.
But the Pedersen did have some drawbacks. The weapon was very precisely machined, and even small errors could throw off its operation. Also, its rounds had to receive a thin coating of wax to guarantee that they'd properly feed through the weapon. Finally, its clips could only be fed in one direction into the rifle, meaning riflemen reloading under fire would have to be careful to get it right.
So, other weapon designers thought they had a chance to win the Army's business. Other .276-caliber designs entered competition, including the Garand.
The Garand could take a beating, was easier to manufacture, and didn't need lubricated rounds. The Pedersen was still the frontrunner in many eyes, but the Garand posed a real threat to it.
Shooting a .276 Pedersen PB Rifle
An even greater blow to the Pedersen was coming. As the move to a .276-caliber continued, the Army Ordnance Department was putting up fierce resistance. The department didn't want to have to set up the whole new supply chain, get the new tools, or prepare the new stockpiles of ammunition required to support the switch.
The Ordnance Department argued, successfully, to Army Chief of Staff Douglas MacArthur that the change would be expensive and present logistics challenges. MacArthur ordered that any new rifle had to use the .30-caliber ammunition already in use by the Army.
Most of the competitors, including Pedersen, didn't think they could re-configure their weapons quickly to accept the larger ammunition, but the Garand team could. They quickly swapped in new parts, and entered a .30-caliber Garand and it won the competition, going on to become the M1 Garand of World War II legend.
But it's easy to imagine an alternate history where the Pedersen or the .276-Garand went into production instead. The .30-caliber ammunition and older weapons would've still seen action, sent forward with Free French, British, and Russian forces under the Cash-and-Carry system and then Lend-Lease.
Meanwhile, American troops would've carried a slightly lighter rifle and much lighter rounds, giving them the ability to more quickly draw their weapons and the ability to sustain a higher rate of fire with the same strain on individual soldiers and the logistics chain.
And, best of all, more lethality per hit. The .30-caliber rounds, the same size as 7.62mm, are more likely to pass through a target at the ranges in which most battles are fought. But .276-caliber rounds are more likely to tumble a time or two after hitting a target, dispersing their energy in the target's flesh and causing massive internal bleeding.
So, if the 1928 Ordnance Board and the modern minds behind 5.56mm and the potential 6.8mm weapons were right, each successful rifle hit by American soldiers was more likely to cause death or extreme wounding.