Yes

28mm revolvers exist they are just not practical weapons (~14lbs).
a 22mm would be almost identical to a 8guage shotgun shell, except it will have more powder.

Hellboy's gun has relatively low power you don't want to copy it.
The length of the cartridge also matters as much as the diameter, a wide short cartridge is not going to pack much punch. Hellboy's cartridges are wide but very short, I would not expect more punch than a large pistol or mid range shotgun.

Your homebrewed cartridges are a bit better, almost identical to a 8 gauge shotgun shell (21.21mm). Homemade 12gauge shotgun revolvers exist and weight around 11lbs, you can drop some weight by using better materials. note your real problem is you have a lot of wasted metal making a cylinder big enough for 6 large diameter rounds, the cylinder needs to be wide enough to fit them all at equal distance which makes for a very large diameter cylinder. That is a lot of wasted metal in the center of the cylinder, and that adds a lot of weight. That is why the largest handguns often only hold 5 rounds, it has a huge impact on weight.

But you could make your bullets a lot better.

So how do you really take advantage of augmentation, use a necked round, you can drastically improve the power for similar recoil. What extreme can you get wit that. well the largest common rifle round is the .50bmg, is 12.7 X 99mm and packs significantly more punch than a an 8 gauge shotgun will.

A .50 bmg handgun also exists (see image) .50 bmg is necked rifle round and produces 65,000 psi (450,000 kPa) and 2-3000 foot pounds of force so a measly 1200 is no problem. Even hand made .50bmg revolvers exist but are comically heavy. A fireable single shot .50 bmg production handgun also exists, THUNDER 50 BMG, it weights 12lbs empty although a significant amount of its mass is recoil absorption.

So in the end you are looking at something in the 10-13 lb range. could a normal human fire it without aid, no, not in any way reliable or combat useful. But an augmented human likely could you just need something to absorb recoil and carry the weight.

You Betcha

If we temporarily ignore the capacity of the wielder to carry the monster, you could weld a hand grip and stock to a Howitzer. Maybe only the Hulk could use it. But it would work just dandy.

So, having proven the premise is possible, let's focus on plausible. I give you:

Recoilless rifles

A recoilless rifle, recoilless launcher or recoilless gun, sometimes abbreviated "RR" or "RCL" (for ReCoilLess) is a type of lightweight artillery system or man-portable launcher that is designed to eject some form of countermass such as propellant gas from the rear of the weapon at the moment of firing, creating forward thrust that counteracts most of the weapon's recoil.

Now, I know what you're thinking. "These are usually shoulder-mounted critters like anti-tank rockets because, well, the back-blast might cause mild skin irritation on the user's face." And you'd be completely correct. But I'm thinking that all we need is some kind of shield, right? Let's think Logan's Run.

copyright MGM

Having done it's work, the back-blast is directed harmlessly out of the user's way. Just because it has the potential to start forest fires shouldn't detract from the natural beauty and form of the weapon. Besides, who doesn't like a picture of Jenny Agutter?

I'm going to leave the ability of the user to hold the weight of the weapon up to the OP. Frankly, I'd hate to hold it on some Evil Genius who's decided to start monologing. No matter how strong you are, that much weight would become uncomfortable mighty quickly. Isometrics, anyone?

Edit:  Daniel B brings up a good point. There's an out-of-manufacture class of weapons that could solve most if not all of your problems: the Gyrojet.

The Gyrojet is a family of unique firearms developed in the 1960s named for the method of gyroscopically stabilizing its projectiles. Rather than inert bullets, Gyrojets fire small rockets called Microjets which have little recoil and do not require a heavy barrel or chamber to resist the pressure of the combustion gases. Velocity on leaving the tube was very low, but increased to around 1,250 feet per second (380 m/s) at 30 feet (9.1 m). The result is a very lightweight weapon.

The Gyrojet is the realization of considerable sci-fi fodder, most notably from the Buck Rogers series of comics (1933) and books where the "rocket pistol" was a staple. I'm especially fond of my copy of Philip Francis Nowlan's Amargeddon 2419 A.D.: The Seminal "Buck Rogers" Novel,¹ (1978) which has a parallel universe, disintergrator rays, and repulsar beams — and doesn't waste one darn minute trying to explain any of them. Oh, yeah....

_{¹ Rendered nearly worthless to anyone but me due to the number of times I've read the book. Yes, I understand there's value in mint condition books — but the true value of a book is discovered by how worn the cover and pages are. Who cares about a book that's never read?}

I've crunched the numbers a bit, and I have to admit that both variants of the weapon are possible, although very unwieldy. What I don't like here is a narrative part - I just can't imagine someone developing such a revolver as a battlefield weapon.

So I've thought about some corrections. Say, we have an increase in human augmentation, robotics, etc. So there are targets that is very hard to take down. I can imagine a government agency developing a ".758 BMG" necked up wildcat of .50 BMG to deal with heavily armored augmented threats in urban environment. The main weapon it used in is a Barret-type rifle, bullpup, suppressed. The round is subsonic and, perhaps, frangible. It has a muzzle energy of about 14000 joules and delivers most of them to the target without overpenetration. It can be fired by non-augmented human operator as an antimateriel rifle, and by a non-augmented operator standing up. .758 BMG rifle is absolutely valid and can be a normal item in your world.

.758 revolver is an experimental crazy offshoot of this technology. It was envisioned as a sidearm for augmented operators, firing the same round. I'm not sure this weapon was ever accepted and mass-produced. It's just too crazy and unwieldy, with too short a barrel for the round it fires. But there can be a number of prototype examples.

For unaugmented human to use it, it needs severely underpowered rounds. And, to be honest, it sucks. Something like .50 Beowulf carbine would give you about the same power (<3000 joules) in much more comfortable and ergonomic package. And all those carbines are of themselves a compromise in trying to fit a big caliber bullet in short action. So it is very much a novelty gimmick and should be treated as such.

Another part that I don't like is that too underload this cartridge you need to leave A LOT of space in it empty. I'm not sure it is safe. My proposed solution was to make the original .758 cartridge caseless. Without brass it would be shorter - maybe around 3.5 inches as opposed to .50 BMG 5 inches. Then the character would be able to manufacture his own weaker cartridges with lighter bullets from cut down .50 BMG brass.

UPD: I kinda forgot your full-power round was supersonic, but IMO, when you go as heavy as 3000 grains, you can just make it subsonic. I envisioned ".758 Barret rifle" as a high-powered analogue to Russian 9x39 rifles, with heavy rounds, subsonic and suppressed, for urban usage.

I can think of 3 ways to solve this problem:

The first approach is to treat it more like a low calabre RPG and less like an actual bullet. Instead of an instantaneous combustion from a cartridge, making the rounds rocket propelled means that the shot accelerates over time significantly reducing the recoil at the moment of launch. 10lb anti-tank rounds can be fired such as to obtain nearly your desired speed within about 30 feet without creating bone breaking recoil. In contrast, a 19.25mm slug will be about 0.1-0.2lb so making a manageable projectile that can reach 800 ft/sec within inches of leaving your barrel should be pretty doable.

A second approach is to treat it like heavy artillery by using hydraulic recoil compensation. By mounting the barrel and firing assembly to a hydraulic track, you can distribute the recoil over time as the barrel and firing assembly moves backwards on the track.

A third approach is to make the slug an explosive round. Explosives are much less dense than lead; so, a 19.25mm explosive round would weight the same as a much smaller solid round; so, you would need a much smaller cartridge to get your shot up to speed.

Absolutely. The trick is, the bullet is a bomb, not a slug. The bullet is a miniature artillery shell with its own destructive mechanism - HEAT, bursting charge+shrapnel, etc.

In fact, that's what requires the large bore - shrinking an "active, fuzed*" artillery shell down to 19mm is quite a challenge**, and this is why modern fighter jets shoot 25 or 30mm rounds.

For Hellboy, this kind of destructive power makes sense given who he's fighting. It also makes it quite an achievement to make his own ammo - the miniaturization.

So the bullet itself is doing most of the heavy lifting - it would be deadly if you handed it to the enemy (presuming this delivery method allowed the fuze* to operate normally).

What does that do for kickback? The gun only needs to get the bullet to the destination. The destruction doesn't depend on imparting a whole bunch of kinetic energy like a normal bullet. That means the launching charge can be smaller, meaning lower kickback. However the large caliber shell necessitates a rather large gun with a lot of mass, which would soak up kickback, making it not bad at all. Anyone who could lift the gun could shoot it.

When Hellboy says "it'll break your arm" he might be exaggerating, or might mean that he's also developed plain old kinetic-energy bullets with a lot of propellant. A bullet that wide would make no sense; surely it would be a sabot.

* Do not edit. The mechanism which tells a bomb or shell when to detonate is called a fuZe. Look it up. A fuSe is something else.

** Part of what makes fuzes a challenge is making them not detonate accidentally. For instance the 16" rounds from Iowa arm from a) 1000++ gees from firing, b) -8 gees from air resistance, and spin from the rifling. Only then, impact+time delay sets it off.

In fact, such guns were actually made, for instance Colt's 10-gauge revolving shotgun: https://www.forgottenweapons.com/colt-1855-10-gauge-revolving-shotgun-at-ria/

(You may be confusing"revolver", which is a mechanism, with "pistol".)