Outside of magical forcefields or slightly implausible improvements in material technologies, suitable guns firing appropriate ammunition will always win. Your teeth aren't going to be any match for a handful of armour piercing explosive rounds, and regenerating an evisceration or severed limb quickly enough to carry on fighting is clearly implausible. You're gonna need magic, or to give up your grand plans, I suspect.

@Starfish Prime, I'm talking about kevlar/carbon fiber level of toughness/strength. Like how vests that can stop 9mm/0.45 acp bullets but aren't stab resistant. Regeneration has been greatly improved (better than wolverine) so stored food is the only limiting factor. Of course the weapons too are made from alloys which are sufficiently tough/strong.

@Starfish Prime I am aware but hitting the limbs and just the torso(say the stomach) simply won't do because of regen, as it'd result in overpentration/non fatal damage. The soldiers won't die unless their core/brain is hit and they will wear armour, so many fights will get into grappling distance.I'm not saying you can't kill a soldier with rifles/MGs but you'd need an awful lot of bullets or luck to hit the core without knowing. I am aware of the most real world limitations, or else it wouldn't have acknowledged my concept as 'Science Ficton'(SciFi) in the question title.

@Starfish Prime all of those exist. It seems you missed my point, I mentioned in my description already that you can penetrate most soldiers with assult rifles/LMGs etc but you wont hit the vitals. And modern soldiers wear ceramic plated kevlar, sure you won't penetrate that with a sword, but you can hit him with a hammer/mace to cause concussive force etc.

That is what the core does with nanobots/ other nerve stimulation. I did say 'placeholder magic' like an infinitely sharp sword etc, i knew how super regen would it'd sound like. Again, while explosive rounds are easier to fire they won't necessarily hit the core if they land next to the soldier/don't penetrate him, but yes if a rpg/gernade launcher's ammo/ tank shell hits a soldier's center of mass he's almost done for.

So, to reduce the level of spam over everyone else's answers: if you have magical wolverine-like regen, then you can have magical flesheating grey-goo like counteragents in bullets. If you don't have magical regen, then armour piercing high explosive rounds fired from large bore weapons like combat shotguns will be quite sufficient.

@Starfish Prime Armour piercing HE rounds do not have remote detonation, atleast the ones used in shotguns. They explode on impact, the primer inside the round ignites and it goes BOOM, it doesn't lodge itself inside flesh and than explode after 30 seconds. Since you call wolverine like regen magic, I assume you will do the same for Star Terk's antimatter propulsion? Grey goos can have counter grey goos consuming them, and it'll be an arms race.

@Rum wolverine-level regeneration via nanomechanisms is magic, just magic that uses sciencey terms in much the same way that Star Trek had dilithium and heisenberg compensators. Delayed detonation warheads can be made that fit into 20mm cannon shells, so by the time that super-enhanced cyborgs are commonplace they'll be able to fit in projectiles that can be fired from man-portable weapons. A nanomechanism arms race will certainly put a substantial crimp in the user's regeneration rate, even if it didn't suppress it entirely.

So you are saying that Star Strek not having containment problems for antimatter isn't magic but wolverine's regen is? Okay. You forget there is a supercomputer with nanobots who can diffuse the explosive shell rendering it as useless as a a round with some primer lodged into flesh which can be removed. I didn't even post the entire scenario of the world just the specific aspect of including melee weapons. But nevertheless it has been helpful and many of my hypotheses have been confirmed.

FWIW, I have no problem with magic, whether old-school swords'n'sorcery or hyperdrives'n'nanobots, but when you ask for a reality check and talk about real world physics, this sort of stuff will be brought up as an issue. Just be honest about the level of speculation your technology involves. People have designed antimatter engines and confinement mechanisms, but wolverine-speed regeneration won't ever feature even in Drexler's wildest dreams. You can't change the laws of physics, as a wise man in star trek said from time to time...

@StarfishPrime heisenberg compensators are magic as well, since there will always be uncertainty in it's measurements since we are being too technical.

That was precisely my point.

The fact that wolverine didn't eat enough was the least of the problems with the speed of regeneration that he exhibited. Structuring that much complex material at that speed requires a colossal expenditure of energy, to the point that the teeniest, tiniest inefficiencies would cook him, at the very least, and probably cook everyone around him too.

The properties of antimatter are reasonably well understood. Working out how it could be made use of, and the properties of the systems that make use of it isn't science fiction. Macroscopic production and long-term confinement remain quite theoretical, but theoretical doesn't mean science-fictional. There's no physical law that would make such things impossible. They're merely impractical.

That was the last comment I intend to make, I was able to find most of the confirmations I was looking for.

Recap: The factions are in an arms race, explosive ammo works but it's usually overkilll, the shotgun ammo you mention is good for stopping cars but has less power than a current frag grenade, with only perk being a bit of range which isn't much impressive compared to ARs.

                          Yes if wolverine is bonding those compounds in his tissues from individual atoms on the spot, not if he already has those muscles prepared and stored so it's essentially like pushing it out. What makes it impractical is the vast amount of energy required to just contain them, by that time , super wolverine regen become plausible.

No, it remains implausible because the expenditure of that energy will release heat. Lots of it. Quickly. That's unavoidable.

Even the storing of enough energy in such a way that it can be discharged that quickly is impractical at best, and probably also implausible.

The perk of the high explosive armour piercing rounds i mentioned is that they're excelkent at killing hard targets, like your cyborgs

and more importantly, they're practical technology right now which means that they can certainly be extrapolated into things that are much more effective by the time you've got super cyborgs. its a reasonable basis for future technology.