Why is 5.56 more powerful than .223, but 7.62 weaker than .308?

>>31898887
Look at the shiny thingy. Obviously the bigger the better

>>31898887
Because thats the design specs

>>31898887
Because you're retarded

http://www.fulton-armory.com/%5Cfaqs%5CM14-FAQs%5C308.htm

>>31898887
5.56 is .223 but a higher standard powder load.
7.62x51 is .308, but again a different standard powder load.

7.62x39 is.... wait fuck me you ARE retarded and I just spent time typing this out for a fucking bait thread.

File: Barret M82A1.jpg (64KB, 1005x655px) Image search: [Google]

64KB, 1005x655px

>>31899017
Atleast we now know you actually know your funs.

>>31899017
wait, so if I have a .308 rifle, I can shoot 7.62x51 out of it? or would there be case expansion issues?

>>31898887
.223 is more associated with low grain 5.56.

>>31899138
It's fine. .308 has a maximum allowable pressure of 62,000 psi and 7.62x51mm has a maximum allowable pressure of 60,191 psi.
There's a potential issue if you were to shoot the higher pressure 308 out of a 7.62x51mm chamber, but it would most likely just result in sticky extraction. Just be aware that there's a tiny risk you're the first guy ever whose rifle is going to fail at 60,192 psi.

>>31899138

The only issue is the very slight difference headspace tolerances for 7.62x51 chambers shooting the slightly smaller.308 case. If you're using quality brass, you can shoot either bullet in either gun.

>>31899146
Not necessarily. 77gr .223 is common for those who want precision and/or longer ranges

Question: if 5.56 has thicker walls why does it usually have a higher pressure than .223? Wouldn't thicker walls mean less powder in the cartridge? Or are there different types of powder and those thicker walls are meant to handle it?

Is this the same case with .308 and x51? Because I hear all the time that 7.62x51 is more powerful than 308 but I've also read that certain BRs can't handle 308 because there's too much pressure...


Explain this to me like I'm 8

>>31899659
5.56 is up-pressured .223 Remington. A 5.56 chamber can safely fire .223 but not vice versa.

Due to how it was developed, .308 Winchester is high pressured than 7.62x51mm NATO. A .308 chamber can fire 7.62 but not the other way around, at least safely.

>Explain this to me like I'm 8
Then the reasons really aren't important.

>>31899659
One important factor determining the maximum pressure a cartridge generates is the leade. This is a measure of how far forward the bullet has to travel before hitting the rifling and encountering resistance. 5.56mm chambers have a slightly longer leade than .223 chambers.
Also thicker walls means a smaller inside volume. PV=nRT.

And .308 is slightly hotter than 7.62x51mm. see >>31899188

>>31899704
Ok that makes sense, I'd never heard of leade.

Thanks senpai

>>31898887
Pressure ≠ power