Not a great description, but I'm guessing a Grade 3 SAC gun with Improved Damascus barrels? I'm also guessing the loose "locking block" reference may refer to the fore iron hanger? I'd call Buck Hamlin in Pevely, MO; 636/479-4304, assuming my memory is correct? This may or may not be an inexpensive repair, depends on how loose barrel ribs may or may not be; but Buck is an honest man in judgment and pricing.