@Thomas Rutledge I wouldn't disparage another member's gun, but since this isn't a member's gun, here goes:
It's about the most useless and overpriced gun on that site at present. A .577 is a ballistically ineffective or inefficient weapon in general, but once brought to tremendous velocity and pressure it works quite well. Once neutered from a Nitro Express velocity/grain weight the bullet is simply too wide in relation to its relatively low mass to penetrate properly on most anything. The gun you're referencing is a diminutive oddball of a ~500gr bullet in .577 held in a 2-3/4" oddball case that will provide only slightly more stopping power than a .50 caliber modern muzzleloader shooting three 50gr pellets. The latter is considered ethical in an inline modern muzzleloader with optics for shots out to ~300 yards max on animals elk and less. (because it drops tremendously and has little energy at reasonable distances) The .577 bullet would make the comparison worse as its like shooting a hubcap it will have such a poor BC and no sectional density.
Now moving that to a double rifle that will never provide accuracy in that caliber and load out to anywhere near 300 yards, the .577 - 2.75" - 510gr load with 160gr of BP is literally a gun for hunting at around 50-75 yards. But then, what will someone hunt with such a gun at 50-75 yards? Kudu? Elk?
Add to that, the gun has a rotted stock (that's what caused the crack...you can see the rot compressions from the wood going soft) and you've got a novelty. I'm uncertain what someone would do with such a marginal bullet at such low velocity. Which kinda brings us to the bullets...they would have to be cast lead with a custom mold, or custom made jacketed bullets because that regulated bullet weight doesn't exist on any shelf.
In short, its the kind of gun that someone would buy for $4000 WITH a good stock to have some fun and shoot at the range. At north of $10,000, the gun is absurdly overpriced and has no particular utility even if the stock was replaced.
Be thankful you have a 3" version that has considerably more use cases than the subject you're referencing above.