In my setting, there's a faction known as International Front that combines guerilla and para-militarism with advanced technology (for a guerilla group).
Their main goal is to fight and conquer the whole world through soft power or military action, and they know that NATO and other conventional forces have the training and technology to defeat or at least suppress an insurgency in the developing world they operate in, let alone the developed world they seek to control in the future.
They have knowledge of advanced technologies from another world, contained in a device of theirs known as the "Book of All Things," but it's encrypted on a level that even teams of experts in cryptography can't break it, and its "ICE" is strong enough to brick the computers they used to install a rootkit.
However, the Book of All Things managed to get hacked open by an ally, and they have full access to the contents within for civilian and military technologies in a variety of fields.
One of those technologies is special type of compound that was used in the other world for firearm parts. It was a lightweight, high-strength material that's often used in a variety of firearm parts.
It could be used for barrel and bolt to lessen weight while retaining the ability to fire high-power ammo without breaking the parts or wearing them away with heat and pressure.
In ammo, it can be used for the case with flexibility modification to withstand larger amounts of powder without case rupture and firearm damage while weighing less than conventional brass, or as part of the bullet itself as a lightweight penetrator for short-range AP ammo that relies on velocity (not mass) to penetrate armor.
It has secondary uses in armor, where in a modified state to increase flexibility and resistance to spalling, it could be used as lightweight body armor plates or armoring for light vehicles to resist AP ammo from HMGs. It can also be used in planes (similar to titanium) to form the body, and does not require sourcing said titanium or special tooling to mill and form titanium.
International Front- once they have the full recipe- use this in a variety of applications. They use this to make a new service rifle based on the AK platform that takes advantage of the material to overcome the AK's limitations.
They start mass producing MANPACs- man-portable autocannons- that can be wheeled like a PM 1910 machine gun and used like a super-HMG against enemy light vehicles and armored fortifications with effective hard-core penetrators that don't require sourcing tungsten and DU. They also start making AT guns like the Sprut-B anti-tank gun that move faster and weigh less making for easier logistics.
Finally, that material lets them start planning for an air force with their own domestic designs and doctrines, planes that aren't copies of the outdated Migs and Sus with the technological limitations of the Soviets, allowing them to counter the air superiority of enemies with F-15s, F-16s and the like.
With all this said, what kind of materials or manufacturing techniques would I be looking at for that kind of lightweight, high-strength wonder material?