Shrapnel, there is no doubt that the gun is well made, and old. A fabulous survivor. But, do you not want to know if the gun has been sleeved, or if it has been re-barreled? I cannot imagine owning a gun that nice and not wanting to know. Hell, I want to know and I've never even seen it (in person).
It doesn't just look sleeved... it certainly is sleeved.
If you look closely, you can see the joint about an inch in front of the engraved forend iron. And if you look even closer, you can see the Damascus pattern in the original breech section. Of course, the Damascus has been blued over and not etched, so it requires a very close examination. Strangely, I can see the sleeving joint and the Damascus pattern better on my cell phone screen than on my computer monitor.
Appearance-wise, it is one of the nicer sleeving jobs I have seen where fluid steel tubes are joined to a Damascus breech section. The joint is very closely fitted from what we can see of it. It would be interesting to know who did the work, and how it was done. There is absolutely no gap or solder joint visible, and it does not look like a TIG welded joint either. The gun is a beauty.