Assume a couple of Tactical Marine Squads are deployed in the Commonwealth wasteland to take out the Brotherhood of Steel. Assume the Tactical Marine Squads operate out of a Thunderhawk in which they have also gear to equip themselves with things like jump packs if needed. The squad also has support from four heavy weapon carrying Devastators + a Techmarine + Apothecary + a single Librarian + three scouts.
Can this force of Space Marines take out the force the Brotherhood of Steel had brought to Commonwealth wasteland?
Probably not.
The reason comes down to logistics and numbers. The loss of one Tactical Marine would effectively mean a drop in 25% of the fighting capability of the main squad. The loss of a single scout would drop intelligence dropping from the scout unit by ~33%. They could reduce the damage by working with a local group and acting as a powerful strike group, but they simply lack the numbers and the endurance to take on an organization that we know in F3 to have had at least 95 named combatants for the BoS and at least 30 or so support. We can probably guess that they had a strength of a company by F3. The size of the deployment in F4 suggests vast growth though and I can't imagine that they'd send something like that airship without significant resource investment.
My guess is that we're probably looking at maybe a full company for the BoS. Including scouts and the like. So a total of 288 combatants and probably about 72 Paladins. So about 10-18 squads, depending on how they break it up. That's a lot of people for four guys to fight. Especially when the BoS is going to have the advantage in logistics, intelligence, and support.
In gameplay, FO is pretty notorious on the inconsistency of how well the armor protects against varying high caliber rounds.
Fallout 3 has a rookie in T-45 solo the Pitt's Raiders and was considered a Juggernaut despite access to 7.62/.308 ammunition in vast quantities.
Previously retconned material stated that FO Power Armor could allow a single user to solo a village/town of Chinese Soldiers who would at least be platoon strength with 7.62 and above ammunition which would be impossible to avoid getting tagged.
New Vegas states that NCR Troopers were able to slaughter half a chapter but on the other hand the courier states even the lense of T-51 power armor is bulletproof.
So honestly we have no idea how good they are against ballistics but the implications is supposed to be VERY good other wise the Chinese need not invent a Gauss Rifle to deal with the America Power Armor just use a good old .308 Hunting Rifle.
One thing is inarguable tho, Fallout Power armors resistance to energy projectiles is incredibly ridiculous that pretty much no energy weapon short of a lascannon is putting a user down.
But they're fighting Marines who use ballistics so bad match up for the Brotherhood lol
Lore makes it very clear that the armor basically ignores 2.5kj and below. The fact is that they can probably resist considerably more, probably something on par with 4-5 kilojoules and still provide ample protection to the user, but probably at the risk of damage to the armor itself. And really, having immunity to 2.5 kj weapons is a pretty big boon on the battlefield.
In regards to laser weapons, it takes ~3 gigajoules to vaporize a human. That's rather excessive, although the games do support considerable levels of vaporization (or disintegration), but it really doesn't make much sense. That's also overkill. A fraction of that energy is probably more than enough to blow someone apart, even if you vaporize a significant amount of them. And those laser weapons would be a far bigger technological advantage than the power armor itself. Most probably, full vaporization of a target is from one of two factors.
1) Longer dwell time on a target.
2) Some sort of malfunction (ie, a critical hit) that causes the cell to discharge all (or most) of its stored energy at once.
We might be able to get a rough idea of how powerful these fuel cells are by looking at the Highwayman. If I'm correct, I believe 1 horsepower is equal to about 735 j/s. It reaches up to 800 hp, so that's approximately 588 megawatts. I sincerely doubt it could travel at that full speed the entire time, but if it can hold that even for say, 10 seconds, that's 5.88 gigawatts. So it certainly seems within the realm of possibility that the microfusion cells can hold that much energy. That said, I just don't think that these people are hurling 3 gigawatts around on the battlefield willy-nilly. Honstly, 30 megawatts is probably the average yield of the laser rifles, with the "critical hits" being a rare, random discharge that deposits 100x the output in one shot, for 2-3 gigawatts of energy, which would effectively vaporize a human target or leave so little left that wasn't vaporized, it wouldn't really matter.
Either way, that shot would probably fuck up a Space Marine (read: kill), but it's basically a random surge on the part of the hardware, so it can't really be depended upon for use in battle. You can probably count on it killing 1, maybe 2 members of the marine squad. Which is still 25-50% of their firepower, but still.
Also, not sure I'd be fully amped to be the guys using gyrojet bullets, given the build-up time you'd need for that and the high likelihood of urban combat. I expect that Astartes use better fuel for their bullets, but you need room for the fuel AND the explosive round. They're basically flying grenades with some good penetrating power. Which isn't anything to scoff at, but there's a chance those things won't instantly penetrate BoS armor. Of course, I doubt BoS armor will laugh it off, seeing as something akin to a frag grenade just exploded on their armor.
