Hello /k/, not sure if this counts as a "help thread"

>>31546859
During the first half of the 20th century most countries where looking toward at least a .30 cal bullet.
Look at the countries that saw combat in WW1 that used 6.5 diameter rounds. Almost every single one converted or attempted to convert to a .30 cal round. Two examples are Italy tries to change to 7.35 Carcano (.300 diameter bullet) and Japan converted to 7.7 Jap (.312 diameter bullet).

>>31546859
Since you're writing the world, either, but 6.5x55 would be much better for a military caliber as .25-06 can only handle 115gr or so bullets which would be outperformed at range. There is the still wildcat 6.5-06 that reworks the cartridge slightly to handle 140gr bullets at which point, they're pretty much identical.

>>31546972
Would making the bullet tail heavy help alleviate this? Similar to how the .303 British MkVII by adding a lighter metal to the nose and thus shifting the center of gravity so that when it hit soft tissue it would tumble violently. Would this grand the smaller 6.5mm round comprable degree of stoping power when compared to its .30 caliber brethren?

>>31547581
That might effect the ballistics on such a small bullet.
But there is other options. Soft point or open point ammo are banned by the Hague Convention in the real world. Who says your world has a similar treaty.

>>31546972
>Look at the countries that saw combat in WWI that used 6.5 diameter rounds. Almost every single one converted or attempted to convert to a .30 cal round.
For the Japanese this had more to do with how they used machine guns at the time. The Italians actually changed in part because it was cheaper to bore out old barrels than buy new ones.

A lot of European countries had advocates for what are essentially intermediate cartridges in the interwar period and some produced prototypes. 8x35mm Ribeyrolles, 7.65x35mm Swiss. Federov wanted to chamber the Avtomat in .25 Remington.

http://quarryhs.co.uk/Assault.htm

>>31548205
Yeah the .25-06 actually started at one of the Arsenals, but the thinking that one out (and persisted long enough to give us shit like the M14) was .30 calibres needed to kill good.

>>31546859

What community OP.

Go with 6.5x55 rip. The 6.5x55 had some interesting loadings for it through its life that let it function in line with small arms doctrine of the interbellum period and even more modern thoughts on all arms, from a 80 grain loading up to 150 grain loadings.

>>31548272
MacArthur pretty much killed the .276 Pederson by himself, even though all the evidence was pointing towards it being a better choice than the .30-06.

The US did it again, like you pointed out, when they nixed the .280 British regardless of what the testing showed.

>>31548410

It was probably overall better that .280 was cut anyways.

>>31548452
Well, it saved the British from fielding an unreliable bullpup abomination. Oh, wait.

j/k EM2 looked pretty sweet.

I don't think it's the worst thing that ever happened, but .280 was right there at the perfect intermediate cartridge. Just look where every effort to replace the 5.56 leads. 6.5Grendel and 6.8SPC do pretty much exactly what 2.80 British did in 1945.

>>31548572

.280 wasn't even really an intermediate. It was closer to what we today call "General Purpose" for some reason, when really it's just a full power.

Individual marksmanship doesn't win small arms engagments, volume of fire does, and that was only just starting to be fully understood by the West as WWII broke out. When the time came to change its actually kind of a good thing the US forced NATO to 7.62x51mm, because it made the US invest more heavily in the SCHV programs they had which eventually lead to 5.56x45mm. had they gone .280 route, they would have found themselves still outgunned by the AKM, which would have higher volumes of fire and ammunition transportability than the EM-2 and other .280 British rifles would have had.

So by forcing mediocre rounds on NATO, the US was able to make the next jump in small arms technology first. Most countries had SCHV projects, but they weren't at the forefront until the US had deployed theirs.

Had they not there wouldn't be the necessity to push to really catch up since it would have been "good enough". The Soviets had plans to roll out their .220 Russian derived intermediate in late 1970s or early 1980s which would have probably been the first SCHV, unless the Germans or British ended up coming through with theirs.

Every effort to replace 5.56 is never seriously considered because 5.56, 5.45 and 5.8 are basically he ideal Infantry cartridges now.

Too, the replacement of .30-06 with .276 may have been troublesome since war was essentially just around the corner, and all Machine Guns would have needed to be changed the same or an expansion of logistics would be needed. It wouldn't have been a war looser but it would have probably caused a fair number more of bodies and drained the economy a bit more.

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>>31546859

.264 USA

>>31548667
.280 definitely sits around the "general purpose" as we're looking at it now, but is definitely an improvement in weight and recoil from the old full power rounds.

I feel like it's adoption would have made the 5.56 class never happen as it would be "good enough" with no real negative repercussions. You're not talking about being outgunned 20-30 more 25-30 for the same weight vs 7.62x39.

I think the big issue with the .280 or 7mm NATO as it would have been called would have been Machine guns. NATO still needed to standardize\ modernize all rounds from the .303, 30-06,8mm, etc. hodgepodge and .280 British being pretty good\ powerful would likely be the first choice. But, as we've already noticed a capability gap between .308 and .50, we'd probably see something like .338 Lapua\ Norma become a standard for medium machine guns as .280 was found to not really have the oomph.

You'd possibly see PDW class cartridges like 5.7 and 4.6 happen a bit earlier for support troops\ possibly urban fighting.

The time wasted in small arms development with the swap from 7.62 to 5.56 to the dicking around with 5.56 replacements could be used to perfect caseless and the G11 gets adopted.

Hypotheticals are fun.