It appears, but I won't swear to it, that it's a Model 557
---snip ---
Kyrie would term it artisanal
Correct. Also, if it is a model 577, Kyrie would term it
bottom price point.
Remington40x, Spanish shotguns dont really come in grades. They are too a la cart for the concept of grade to have much meaning. Its generally more meaningful to talk about the relative amount of skilled hand labor that goes into two or more guns when trying to do comparisons. Price point of a gun and the amount of skilled hand labor that when into the creation of the gun are highly correlated, hence the references you will see to price point.
As an aside Arrieta dropped the model 577 from their catalog, making the model 578 the current bottom price point Arrieta.
As a reference, any VS side lock gun with 30% or more engraving coverage will have more skilled hand labor in it than the run-of-the-mill 577 or 578
