You are asked to design a new caliber of bullet for the following

.5318008

>>32505913
>optimize for a distance most likely to be used in engagements in urban areas

and

>400m
>800m
>1600m+

These two requirements are directly contradictory. 5.56 carbines are complete ass past 200m, but everyone is moving to them because almost all urban engagements are under 150m.

>>32505913
>100m
>400m
>800m
.30-06

>1600m+
.50BMG

Who do I see about getting paid for my groundbreaking achievement?

100m+ 7.62 nato
400m+ 50bmg
800m+ 30mm

>>32505913
What's the intended purpose of the cartridge?

a cartridge that works in a platform that can fire different cartridges, same chamber size but a bolt that accommodates a larger casing, so you swap bolt, mags, and ammo. Boom. multipurpose gun.

>>32505913
1600m+ one is going to have to be RAP to make common chamber even a little useful.

So most important question is how small can a specialized RAP/base bleed round be made, one that gets kind-of sort-of out to 1600m?

5.56?

>>32505913
.458 Lott for all

>>32505913
.666 CMC

>>32505913
So what are the restrictions?
Do we have to make this work with an existing platform (AR or AK for example)?
Can we designate this will be fired out of a new unspecified gun? If so, is it a semi/full auto or bolt?
Are we restricted to existing powders?
What are our pressure limitations?
Do we have to use existing bullet designs/technology?

Without any restrictions, what is stopping me from necking down an artillery shell to .270 caliber using space magic powder that won't burn the rifling away or cause a case rupture?

Also
>Urban combat
>Anything past 200 yrds?

Also also
>1600
Call in airstrike/artillery.

>>32505913
7.5 Swiss

>>32506622
We can call it: the ACR

>>32505913
Someone already has..

.959 JDJ.
It's effective at all of these ranges.

>>32508409
I don't get the joke.

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>>32505913

That 1600m kinda throws out the 6.8, maybe even 6.5, so maybe .264 USA?

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>>32509050

*Or LSAT 6.5?

>>32505913
.338 to .50 caliber belted magnum. Headspace on the belt means you can cut and use a big chamber for long range work or use a cartridge with a shorter shoulder and longer neck for shorter distances.

.243 Winchester AI

>>32506622
>same chamber size
>bolt accepting different casings

That isn't how it works, noguns

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>>32509158
270WSM

>>32505937
first post best post

>>32509346
That isn't as hard to do as it sounds at first blush. It's really simple with a rear locking bolt like a SMLE or MAS 36. Could be done with a semi or fully automatic as well. Just use a longer bolt to take up the rear of the chamber. Mags for the shorter round could be blocked at the back so the round sits forward and the longer bolt has room to pick it up. You'd need to use blowback or recoil to move the bolt, not direct impingement. Both cases would preferably be rimless bottleneck types with a common shoulder diameter.

>>32505913
>100m 5.5x19 (.22lr boolit in a necked down 9mm para case)
>400m 6.5x51mm
>800m 7.5x70mm (slightly necked down .30-06 in a longer case)
>1600m+8x100mm (necked down .50 bmg in a longer case)

chem-rail
Chemical propellants get the bullet to 400m effective range, electromagnetic rails push it further if need be.
Smooth bore discarding sabot, some kind of super dense metal for the dart.

>>32509689
>longer bolt to take up the rear of the chamber
It works a lot better in theory than in application.
how do you extract the spent case when you have an FTE by design? where do you put the ejector without compromising bolt/chamber support? chamber support is already shoddy at this point since youve separated the chamber at critically weak points so you have to beef it up to compensate, end up with chamber walls that are 30% thicker at best and are more prone to failures to go into battery, because you not only have locking lugs to headspace, you now have to worry about headspacing the chamber faces as well
>or would it be headspacing headspace?
which is now a massive surface to get shit stuck between. now do you go AK loose or AR sealed to prevent this? it doesnt matter because your 308/300blk/300wm abomination now weighs 12 pounds unloaded without furniture or optics or FCG because how are you going to adjust the firing pin strike point for your caliber changes?

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>>32505913
20mm necked down to .50

>100m
>400m
>800m
>1600m+

Everything dies.

>>32509477
Uncontrollable in full auto. .243 is pretty much the max one can go in that regard.

>>32509842
>I like your interpretation of OPs dumb game

>100m
6x40mm, basically necked up 5.45x39, max COAL 60mm
>400m
8x50mm, a slightly shorter 7.92x57mm, about 75mm max COAL
>800m
8.6x60mm. pretty much .338 norma mag
>1600m
you should be using a drone. or Tiborasaurus Rex

.243 55gr +P+ APFMJ (6,500ft/s)

>>32505973
>but everyone is moving to them because almost all urban engagements are under 150m.
If you go to dictatorship shitholes, you'll notice they love to build these kilometre-long, six-lane-wide avenues leading up to the presidential palace and/or national assembly, so it could be useful.

>>32505913
>You can use different loads for different distances but the projectile size cannot change
>You can also change the shape of the projectile if needed
am i retarded or is this a direct contradiction of your own rules?

>>32510564
>>32509842

ez mode
100m 9×39mm
400m 5.8×42mm
800m 7mm Remington Magnum
1600m 20x110mm Hispano

>>32505913
https://en.wikipedia.org/wiki/9.3%C3%9762mm

nice one retard

7mm08.

Regular infantry have no requirement to engage 1600m if theyre lacking mortar/gpmg support.

/thread

10mm auto

>>32508862
underated