WI: US Army adopts Garand rifle in .276 Pedersen?

How would small arms develop if the US adopted an intermediate intermediate cartridge (between assault rifle and battle rifle caliber) in the 1920s-30s? The way I understand it, the military started realizing that the M855 5.56mm round just wasn't enough, and evaluated 6.5 and 6.8mm cartridges throughout the 2000s. They also weren't alone in the 20s and 30s either, since the Japanese had their 6.5mm Arisaka.
 
Wasn't Gonna Happen

It just isn't going to happen due to economics. The Army's budget was miniscule in the inter-war years plus the Army had millions of .30-06 rounds in storage. While people always criticize MacArthur, his call to convert the Garand to .30-06 was the best option, otherwise there would only have been a handful available for WWII.

While all the major powers were looking at Intermediate caliber rounds, the advantages just didn't outweigh the costs of switching, especially for a semi-automatic weapon. It wasn't until the StG44 was introduced that the benefits of the Intermediate caliber round started to outweigh the costs.

Even then the US Army still tried to make the large caliber round work in an automatic rifle (M-14) which wasn't successful.
 
Millions of old 30-06 could still be used in machine guns and BARs

Those old rounds in the warehouses were not stripped out of old ammo belts and Springfield stripper clips, new 30-06 rounds were made to go into those new en bloc clips.

It was false economy, like the Civil War monitors were 'repaired' into new ships in the 1880s
 
M1 Garands in .276 aren't going to be any better than those in .30-06, unless you give them BM59 features like a 20/30-round magazine and full auto capability.
 
M1 Garands in .276 aren't going to be any better than those in .30-06, unless you give them BM59 features like a 20/30-round magazine and full auto capability.

firing tests showed the 276 more accurate from lower recoil, and it was a 10 round clip.

Army did not want detachable mags that protruded from the belly.

One of the early Garand prototypes used modified BAR mags.

Interfered with the Manual of Arms, so was told to get rid of it.

yeah, a BS excuse. But that's why the Garand and Johnson rifles were the way they were. Army Brass knew what the Rifleman needed.
 
I was under the impression that standard .30-06 was too hot for the M1 anyway and could bend the op-rod, so they had to manufacture a modified version, which cuts into the logistical reasons for sticking with .30 caliber.

Having different MG and rifle calibers isn't great, but U.S. machine gun doctrine wasn't great anyway; the rifle was supposed to provide the squad's base of fire, so more, lighter ammunition for the rifle would more than makeup for any MG firepower lost because of ammo non-interchangeability.
 
firing tests showed the 276 more accurate from lower recoil, and it was a 10 round clip.

Army did not want detachable mags that protruded from the belly.

One of the early Garand prototypes used modified BAR mags.

Interfered with the Manual of Arms, so was told to get rid of it.

yeah, a BS excuse. But that's why the Garand and Johnson rifles were the way they were. Army Brass knew what the Rifleman needed.
There was also the WW2 T20/T22 Garands, with selective-fire capacity and various magazine options. IIRR the attempt to use BAR magazines was one of the factors that delayed the project.
 
I was under the impression that standard .30-06 was too hot for the M1 anyway and could bend the op-rod, so they had to manufacture a modified version, which cuts into the logistical reasons for sticking with .30 caliber.

Having different MG and rifle calibers isn't great, but U.S. machine gun doctrine wasn't great anyway; the rifle was supposed to provide the squad's base of fire, so more, lighter ammunition for the rifle would more than makeup for any MG firepower lost because of ammo non-interchangeability.

I think that might have been an issue with the M-1 carbine, which used a lower power .30 cal cartridge. AFIAK the M1 Garand used the same .30-06 as the Springfield and the M1919 and M1918 machine guns.

Besides, given the millions of rounds of .30-06, the US would not adopt a rifle pre-war that needed a different cartridge. The failure to switch to an intermediate cartridge post-war, is much less excusabe.
 
Besides, given the millions of rounds of .30-06, the US would not adopt a rifle pre-war that needed a different cartridge. The failure to switch to an intermediate cartridge post-war, is much less excusabe.

But did introduce the M1 Carbine with all new ammo.

Army still had millions of 30-40 Krag still sitting in warehouses. All new rounds were made for the M1, they didn't take that old Springfield ammo in stripperclips or BAR ammo in mags and put that in en bloc clips, it was all new ammo contracts.
 
I was under the impression that standard .30-06 was too hot for the M1 anyway and could bend the op-rod, so they had to manufacture a modified version, which cuts into the logistical reasons for sticking with .30 caliber.

and the first ones used a gas trap, rather than porting the barrel.
But it did take time to toughen up the M1 to use 30-06 reliably

The 30-06 M1 Ball used a 172 grain bullet, made mostly for machine gun use, not the M1 Garand. Too much recoil

The M2 went back to the original 150 gr. 1906 bullet, and became M2 Ball in 1938

M1 Ball was still made for USN contracts thru 1941
 
The 30-06 M1 Ball used a 172 grain bullet, made mostly for machine gun use, not the M1 Garand. Too much recoil

I have never before seen a mention of M1 having any issues with recoil. The usual explanation is that M1 was developed to overcome the pathetic ballistics of the WW1 bullet and so give US machine guns comparable range to UK/FR/DE machine guns. This then led to M1 routinely shooting out of the firing ranges designed round the original loading and the Army deciding that rather than spending a fortune buying land to enlarge ranges, they would revert ballistics that they had a few years previously decried as dangerously inadequate.
 
Given that a stripper clip fed Garand in .276 would perform fantastic, do you think other countries would follow the U.S.'s lead? I know the British experimented with a 7mm bullpup before being forced to give it up for 7.62 NATO, and the Japanese already had a 6.5mm cartridge in wide circulation; would other countries lean more towards the short, stubby 7.92x33mm and 7.62x39mm cartridges that the Germans and Soviets used, or the .276 Pedersen round?
 
Given that a stripper clip fed Garand in .276 would perform fantastic, do you think other countries would follow the U.S.'s lead? I know the British experimented with a 7mm bullpup before being forced to give it up for 7.62 NATO, and the Japanese already had a 6.5mm cartridge in wide circulation; would other countries lean more towards the short, stubby 7.92x33mm and 7.62x39mm cartridges that the Germans and Soviets used, or the .276 Pedersen round?
The British gave serious consideration to adopting the Pedersen rifle in .276 in OTL - if the US had adopted it then the UK might just have tipped over the edge and used it too. Garand in .276 isn't nearly as likely though IMHO.
 
IIRC, the Pedersen rifle had issues that made it inferior to the .276 Garand in some respects, like needing waxed cartridges and being more vulnerable to dirt and mud entering the toggle lock mechanism. The British might still have adopted the Pedersen for ammo commonality alone, but I don't think the U.S. Army was going to contract for it.
 
If the US army had taken a longer term view then the idea that they should retain 30-06 due to having stocks of the stuff doesn't really add up. For starters the existing stocks of .30-06 pretty much evaporated within a few months of Pearl Harbour. Each .276 would have used less propellant and brass so each round had a smaller logistical footprint than the old 30 cal. Each infantryman could carry more ammo for the same weight and the rifle had a larger magazine capacity at 10rounds.

The point that the existing MG's would required replacement is not necessarily a good one. Most could have been rebarrelled in .276 but have required the rear sight being replaced to account for the altered ballistics of the new round.
 
The main issue would be using diferent ammo for rifles and MG, which was not regarded as acceptable at the time. Virtually all WW2 era armies used the same ammo for their rifles and their MG ending up with overpowered rifles rather than underpowered machine guns. A few countries used heavier rounds for their heavy MG, keeping the rifle caliber LMG. The Swedish army even made a rifle for their heavy MG round, so that the HMG crews used only one type of ammo, ending up with a rifle that was too overpowered for infantry use.

The use of a different caliber for the carbine was tolerated because it was regarded as a new class of weapon, in fact a PDW meant to replace pistols and SMG.

Of course armies routinely supplied parts for a multitude of different equipment and managed to deliver the right parts to the right unit, but somehow ammo supply was regarded as something that had to be kept as simple as possible.
 
The main issue would be using diferent ammo for rifles and MG, which was not regarded as acceptable at the time. Virtually all WW2 era armies used the same ammo for their rifles and their MG ending up with overpowered rifles rather than underpowered machine guns. A few countries used heavier rounds for their heavy MG, keeping the rifle caliber LMG. The Swedish army even made a rifle for their heavy MG round, so that the HMG crews used only one type of ammo, ending up with a rifle that was too overpowered for infantry use.

Then there is Japan and the UK

The 6.5mm Type 11 MG and Type 96 used a lighter load than the rifle load.

IJN 7.7 was different from IJA 7.7

while the IJA 7.7 MG round was semi-rimmed to prevent it from being fired in rifles, as it was too powerful. Rifles used a rimless round.

The Navy round was fully rimmed, and a copy of the 303 British.

Now the Brits had a hotter version of the .303, called the Mk VIII, expressly for Vickers guns. It caused bore erosion in everything else, and had many tank machine guns chambered in 7.92mm, functionally identical to the German 7.92mm round
 
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