Exactly!
Too bad.
As an aside, what do you think of the “conversion” or what that could mean?
I myself, suspect that it could be that A&N could have rechambered and regelated it for a flatter shooting 577 and the rear sight leaves were altered or replaced for the flatter trajectory.
Then, perhaps, someone along the line fired a nitro load in it and cracked the action.

BTW, I pointed this out to the seller.
Will see if he pulls the gun or discloses this major flaw.
Pretty much shoots his entire condition description down in flames IMO.