The bore on the blown rifle bbl looks awfully rusted. Maybe in 7x57 and the ammo being used was ancient 7x57 Milsurp corrosive primed.
Left as-is after the destruction of course, so it rusts very aggressively.
If the undamaged bbl is rusted the same then I'd think the corrosive ammo theory would be a good bet.
Whether Military ammo or not, who's to say.
Perhaps a bullet jammed in the bore from a squib-fire. Thinking a misfire and not even looking at the extracted and discarded bulletless round, another was quickly loaded and fired behind it.
Looking at the bbls on both sides just forward of the action flats, there appears to be an area on both sides that resisted bluing.
Easily seen on the left tube pic #13. Less apparent on the right but still able to be seen in pic #6.
Could the bbls be a re-tube using the breech section of the orig bbls as a monobloc. Then the seam where the tubes join been welded over to hide that joint.
The welding being the cause for the bluing issue.
The bbls have been re-blued for sure as there are areas of pitting along them still underneath the bluing.
The US style cross-wise dovetail front sight seems out of place on something European and 125yrs old as well, maybe not?
Too bad about the damage. Could still be a good project I think but an in hand inspection would be my preference.
Just some thoughts and I already have too many projects and too little time.
