The 520 series pumps are great shotguns.
The 520 was the field grade. 522 the straight stocked Trap gun.
525 made to order fancy wood and checkered but no engraving.
The 535 was the top of the line. Made to order, engraved, best imported walnut, checkering, ect.
Hollow matted rib avail on the 522 and up.
Lots of engineering changes along the production life. Early (pre '15?) guns had a hang fire safety in them.
They had the same run up in class in the Models with their Model 425 Lever Action Rifle. The HighGrade offerings rarely seen as with the 520 shotguns.
Their higher grade SxS's aren't too hard to look at either.
added..
Is this the 535 in the OP?
Not many around.
http://archives.collectorsfirearms.com/?page=322&category=&product=s4245
