.338 NM Lightweight Medium Machine Gun (LWMMG)

To me..................The big advantage of this new machine gun is, it will shoot a lot flatter than the 7.62. A 1 to 2" bullet drop with the 338 will produce more hits than the 7.62 when you're holding 12 to 16" for same distance shots. Now if you want to talk 7.62 vs. 5.56........That's a whole new kettle of fish.

This gun is very close to one I designed for a game concept back in 2008.
I think its excellent that someone got the idea that our current .308s are the new 5.56, and the 308 is no longer the big dog it once was.

Why the need for all the heavy firepower? In the game, by the 2030s all the solders were wearing really good body armor that covered the whole body (think nanopolymer liquid armor). Other nanocomposites like graphene were also being folded into the mix. Soldiers could swap 5.56 and 7.62ak all day and would probably run out of ammunition and have to resort to pulling out the army shovels before the battle was decided. Or they could just use better stuff. Shooting someone directly with a 40mm grenade was a valid tactic (and usually decisive, usually that is).

Someone else here asked why you need so much firepower... the reason is because whatever a gun will currently do at point blank range, more firepower means it will be able to do that several hundred yards downrange. For the .338 NM shooting at something 500 yards away might have as much firepower as a .308 at the muzzle. Thats brick splitting power. The ability to penetrate, or not penetrate, is a pass/fail test.

The general purpose machinegun that closely mirrors this .338 NM gun in real live was called the M-100 and was chambered in a variant of .375 Ruger and loaded from 120 round belts. It had a 600 round per minute fire rate and a quick 2 shot burst feature mode (1500cyclic) which turned it into a mild sniper platform alot like the M2 Browning was known to be used for (if the first one misses, the second may hit anyway). It also had a set of 2 composite barrels which could just be rotated into place on the field (talk about a fast barrel switch) and altogether it weighed 25 pounds.

The round was actually a 250grain 7mm Fin Stabilized armor piercing Sabot deeply seated into the cartridge but by the concept it could chamber .375 Ruger. Because of the flat trajectory and the fact such a long flechette-style projectile would tumble on hitting a soft target it had almost the same penetration and damage as a .50cal.

The assault rifles of the world were also upgraded to a round with minor differences to the 6.5mm Grendel with the variant type designation APSFTBT - armor piercing semi frangible tumbling boat tail.

The pinnacle of that technology was a rifle I designated as the FN-125 which fed from dual 60 round magazines, side mounted at an angle and lengthwise along the weapon similar to a P-90 (when one empties, it switches to the other), with a forward cartridge ejection system (at that time I did not know about the Kel-Tec RFB). The bottom portion of the gun was a semi-automatic high pressure 30mm grenade launcher with a strong muzzlebreak, with a 5 round magazine on the bottom. The grenade launcher had a buckshot load, so you either get 120 rounds of pure death and you can reload the gun at your pleasure, or 5 shots of (3 gauge?) shotgun to the face. Weighing in at 12 pounds it also had a comprehensive tech scope on it that could program grenades for early detonation. Dont even bother waiting for them to stop to reload, that tactic dont work.

I also had a redesigned P-90 with dual feeding magazines (x40) chambered in 10mm Auto, which had special sabot slugs designed for it that delivered armor piercing pdw performance (they just took 5.56mm slugs and sabotted them for the 10mm caliber). Made almost completely out of composites thats 80 rounds of lightweight fast firing death.

And there was a .50 caliber man portable machinegun, it was the M-192 Heavy Repeater, an assault-rifle style gun with a dual drum 40 round magazine and a massive muzzle break on the end that looks like a honeycomb, though it had other recoil dampening systems too similar to the OCSW (and an awkwardly oversized arching carrying handle on top which was part of the recoil system). Firing at 300 rounds per minute it had as much kick as a shotgun. Designed as a limited purpose entry weapon because the 24" barrel wasnt built for excessive range accuracy, and well .50cal rounds are heavy as hell.

They replaced main battle tanks with lightly armored vehicles armed with high velocity missiles (read: Starstreak) that could do the same job. You dont want to be sitting out in the open in a big tank that 3 vehicles could open fire on out of nowhere and take you out. The vehicles had similar liquid armor in their walls but it was alot stronger.

But the real threat was from the UGV (unmanned ground vehicles) which were ruggedized tank platforms the size of an ATV, that could take their hits and keep smiling, and even had backup weapons in case their main guns got jammed or damaged. Mass produced, these became a fighting staple and forced everyone to upgrade their firepower, you had to be able to shove enough 30mm and 40mm grenades at these things or fire away with enough 7mm Sabot to take them out otherwise you were just dead. Everything the UGVs were armed with had lots of belted ammunition and was super dangerous.

No it was not a terminator video game. It was a tactical RTS similar to the XCom storyline involving a secret alien takeover.