From what you describe and from the 2004 catalog - you have a B525 Classic 12M (Magnum) 'Hunter' (invector chokes). It came in Elite Gr III, Prestige Gr V, and Ultimate Gr VI. A 'Hunting' model had conventional fixed chokes.
The catalog lists: (and is DAMN confusing)
Hunting Firearms:
B525's
Classic 12 Hunting (fixed chokes) / Hunter (choke tubes) 24", 26", 28" bbls.
Classic 12 or 20 Magnum in Elite Gr III, Prestige Gr V, and Ultimate Gr VI
Classic Light 12 2-3/4" chambers
425's,
Classic Light (Hunting/Hunter) 20 2-3/4" chambers
Classic Light Elite 28ga and .410
Specials - Privilege in 12M and 20M plus Waterfowl and Special Waterfowl Camo
Hunting and Target Firearms:
GTS 12M Gr I, and Elite
Target Firearms:
Ultra XT, XTR, XTR Midas, XS, XSH,
with Ultra SX subcategories of Sporter, Sporting, Sporting Ported, 20ga Sporting.
Ultra Sporting (fixed chokes) and Sporter (choke tubes) - (available in left-handed model)
Ultra Trap (available in left-handed model)
Ultra Skeet (NOT available in left-handed model)
B525 Sport
Sporter/Sporting 12 & 20 (standard 3" chambers but not available in less than 28" barrels)
(Sporter 12's available in Elite Gr III, Prestige Gr V, and Ultimate Gr VI)
NEW Sporter 20 in Elite Gr III and Prestige
New B525 Trap (2-3/4" chambers
Browning confused the public and themselves with all the designations for a multitude of available options - as Vette Jockey said, the return to '131' code only negated or simplified the product 'code' confusion......not product 'line'.