US adopts 6mm caliber in 1930s

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You can't go far wrong with a Mannlicher en-bloc clip. Pointy stick stop go bang. Metal thingy on top stop stay open. Feed hungry rifle spirit with clip. Close metal thingy. Stick now go bang again.

No fumbling with magazines. Used clip just falls out and is no longer needed. Ammunition comes in clips. What the box magazine does is allow more rounds in one unit and can be topped up with single rounds which rarely ever happens and yes you can reload a clip with loose rounds.
 
You can't go far wrong with a Mannlicher en-bloc clip. Pointy stick stop go bang. Metal thingy on top stop stay open. Feed hungry rifle spirit with clip. Close metal thingy. Stick now go bang again.

No fumbling with magazines. Used clip just falls out and is no longer needed. Ammunition comes in clips.
Provided you haven't cocked up the clip design so it only goes in one way.
 

perfectgeneral

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Gas operated rotating bolt assault rifle (6.5mmx50.5mm rounds).
It says here that, from 1932, Swiss company Oerlikon owned the foreign/international rights to the design. So the US/UK could manufacture under license. SI victims take note!
 
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SwampTiger

Banned
I doubt the US Army will accept a 6 mm or smaller cartridge before WW2. The Navy had experienced issues with bore wear and possible failures to stop Philippine fighters with the 6 mm Lee. The early high velocity cartridges of the day were still novel experiments. The Army was conservative. It was considering smaller caliber cartridges. Early experiments favored 6.35(.25) to 7(.28) caliber cartridges. The .276 Pedersen or a rimless 6.5 Arisaka would have been perfect.

The Scotti open bolt would not be acceptable for the US Army marksmanship requirement. The heavy thump during firing would reduce target shooting scores.
 
When the Swedes adopted their 6.5mm Swedish Mausers, they eventually decided to chamber their machine guns in 8mm Patron m/32, which was basically 8mm-06 with a wider case (170 gr at 2,800 fps) to fit in Browning actions. Any cartridge smaller than 7 x 57 Mauser would probably require this kind of split with pre-1930 propellants.
 
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SwampTiger

Banned
When the Swedes adopted their 6.5mm Swedish Mausers, they eventually decided to chamber their machine guns in 8mm Patron m/32, which was basically 8mm-06 with a wider case. Any cartridge smaller than 7 x 57 Mauser would probably require this kind of split before about 1930.
The US had a solution after 1906.
 
The original caliber testing, started by the Army in 1925, found that an oversized .25 was the most effective of all, over the .276 and .30, for the report of the "Pig Board" tests in 1929

It had a 125 grain bullet@2659fps with a 55.9mm long case.
 

Deleted member 1487

Gas operated rotating bolt assault rifle (6.5mmx50.5mm rounds).
It says here that, from 1932, Swiss company Oerlikon owned the foreign/international rights to the design. So the US/UK could manufacture under license. SI victims take note!
They already had a gas operated, rotating bolt rifle design...the Garand and M1 Carbine. Which were turned into the AK-47 by the Soviets, who liberally borrowed from those designs.

I doubt the US Army will accept a 6 mm or smaller cartridge before WW2. The Navy had experienced issues with bore wear and possible failures to stop Philippine fighters with the 6 mm Lee. The early high velocity cartridges of the day were still novel experiments. The Army was conservative. It was considering smaller caliber cartridges. Early experiments favored 6.35(.25) to 7(.28) caliber cartridges. The .276 Pedersen or a rimless 6.5 Arisaka would have been perfect.

The Scotti open bolt would not be acceptable for the US Army marksmanship requirement. The heavy thump during firing would reduce target shooting scores.
The Lee Navy was harmed by the shitty metallurgy of the day, which meant the barrels weren't up to modern powders. Not an issue by the 1920s.
Plus the reports about stopping power in the Philippines weren't corroborated, in fact the fighting in Cuba showed very different results.

You're right that the caliber studies looked into 6.5mm-7mm as the ideal (the Kent Report from the OP took those results even further), but the conservatives went as big bore as they could and settled on 7mm; the .276 Pedersen was far from perfect, but it was the best that could be gotten through the infantry board at the time. The Arisaka is better, but still not really ideal.

The Scotti was meant as an anti-aircraft gun for defense against low flying aircraft, so of course it was meant to work as an automatic, but that wasn't hard to change if desired.

When the Swedes adopted their 6.5mm Swedish Mausers, they eventually decided to chamber their machine guns in 8mm Patron m/32, which was basically 8mm-06 with a wider case (170 gr at 2,800 fps) to fit in Browning actions. Any cartridge smaller than 7 x 57 Mauser would probably require this kind of split with pre-1930 propellants.
They only adopted the 8mm for their heavy machine guns because they were meant to be an anti-material/anti-aircraft weapon and very long range. So they wouldn't even take the 8mm Mauser and instead mated the Mauser caliber to the American .30-06 cartridge case to push the 8mm bullet to the max as well as be able to use the heaviest bullet possible. In a sense it was their 9mm MAS/.338 LWMMG.

Frankly the other Europeans and Americans should have accepted that the ideal solution for an MMG/HMG and an infantry rifle/LMG would be so different that it would require different cartridges. Give it to the Swedes for being ahead of the game.

The original caliber testing, started by the Army in 1925, found that an oversized .25 was the most effective of all, over the .276 and .30, for the report of the "Pig Board" tests in 1929

It had a 125 grain bullet@2659fps with a 55.9mm long case.
Indeed, which I think led to the Kent Report in OP about small caliber high velocity rounds being the most lethal.

BTW where did you find info about the case length and muzzle velocity? I've been trying to find info about the Pig and later Goat Boards and can't find the reports.
 
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Deleted member 1487

Hypothetically speaking, if say something like their the .276 Pedersen or the 6mm proposed in OP were adopted...could we see a select fire, box magazine Garand replace the BAR at the squad level? Effectively an early M14, but with substantially less recoil and thermal build up.
 
BTW where did you find info about the case length and muzzle velocity? I've been trying to find info about the Pig and later Goat Boards and can't find the reports.
Old Factoids from USENET, long ago. You would think Hatcher would have had more on that history, but info if pretty thin. Even digging around, can't find the original report online anywhere, just other things referencing it.
 

SwampTiger

Banned
Hypothetically speaking, if say something like their the .276 Pedersen or the 6mm proposed in OP were adopted...could we see a select fire, box magazine Garand replace the BAR at the squad level? Effectively an early M14, but with substantially less recoil and thermal build up.
If you can get the 6 mm adopted through Ordnance, you could get at least a chance at some of your wish list.
 
The Scotti is lever delayed, so not open bolt.
these are not exclusive
the lever delay action holds the bolt closed long enough that it's safe for the action to cycle
open bolt just means that the bolt sit at the back of the receiver. pulling the trigger releases the bolt and allows it to move forward, pick up a cartridge, and fire

gj to the rescue
 

Deleted member 1487

The .276 Pedersen or a rimless 6.5 Arisaka would have been perfect.
So after finding some info about how the .276 Pedersen compared to the .30-06 on the Forgotten Weapons website, though still not ideal the Pedersen cartridge compared much more favorably with the .30-06 than I thought. I'm assuming they're talking about the version that did not share the same base diameter with the .30-06. I'll post a picture of the article that details the advantages of the Pedersen cartridge when I get home, but the advantages included much lower heat build up, allowing for 500 rounds vs. 200 for the same heat load on the weapon. On top of that it had about half the felt recoil. There were other advantages as well, but it really makes it seem like no brainer to have used that cartridge over the .30-06, even if it was imperfect in hindsight, especially for an automatic weapon.

Seems like a Johnson LMG in 7mm Pedersen would have been about as perfect a SAW as would have been available in the 1940s since it would be able to be made lighter due to the lower recoil plus fire over twice the number of rounds before overheating.
 

Deleted member 1487

Ok, here was the article page:
https://www.forgottenweapons.com/m1-garand-development/us-pedersen-276-rifle/
pedersen63.jpg


Given the figures, I have no idea why the Brits didn't adopt the Pedersen 7mm bullet for their .280 cartridge other than having slightly more case capacity with the flat base bullet and their fetish for flat base bullets (easier manufacturing, slightly less barrel wear?)
 
Thanks for the article Wiking. You may well be able to get an answer from Tony Williams, as he is quite knowledgeable about pretty much everything Small arms in the UK's arsenal.
 

Deleted member 1487

Thanks for the article Wiking. You may well be able to get an answer from Tony Williams, as he is quite knowledgeable about pretty much everything Small arms in the UK's arsenal.
I'm pretty sure I can piece it together from previous British armaments development and reading between the lines of studies done on the development of the EM-2 like this thesis:
https://kclpure.kcl.ac.uk/portal/files/2931678/540222.pdf

Basically since they wanted a universal cartridge with enough lethal energy at 2000 yards to make it usable in a MMG as well as appease US military demands, they had to have a minimum weight. The Pedersen bullet with the boattail was only 125 grains, while a flat base bullet allows for a heavier bullet for the same length, which resulted in the final S12 bullet for the .280 at 140 grains, the same standard bullet used in the 7x57 Mauser. In terms of bullet energy there is no replacement for displacement. The .270 British couldn't be made heavy enough to meet the requirement laid out by the US for energy at 2000 yards and still meet the desired muzzle velocity, trajectory, and recoil requirements within the time constraints to develop the new cartridge, but the .280 could.
 
There's a bit in the write up about the bullet being a "true 7mm", .284 inches in diameter...I know when I divide 7 by 25.4, I don't get .284, WTF?
 
There's a bit in the write up about the bullet being a "true 7mm", .284 inches in diameter...I know when I divide 7 by 25.4, I don't get .284, WTF?
The caliber is the barrel diameter between lands, not the bullet diameter. A 7 mm (.277 in) bullet is fired out of a 6.8 mm (.270 in) barrel. A 7 mm (.277 in) barrel fires a 7.2 mm (.284 in) bullet.
 
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