Here is the description from a Morphy Auction, 31 October 2018:

Of all Mannlicher Schoenauer carbines, those with this very graceful and superbly fitted full length ribbed barrel are the rarest and most desirable. This carbine has 20" barrel of Boehler Antinit steel ("Antinit" engraved on left side). The full length matted rib is fluted on both sides and is fitted with one standing, one folding leaf rear sight and silver bead front longitudinally dovetailed into muzzle end. Typical Mannlicher Schoenauer action with all correct markings and proofs has sculpted front radius as transition to rib. It is fitted with the Schoenauer rotary magazine, has typical butter knife bolt handle, and double set triggers. Cocking piece is fitted with Lyman aperture sight. Lightly fiddle figured and somewhat streaked European walnut full length stock measures 14" over steel buttplate with trap which covers space for two cartridges (not present) and four piece cleaning rod (which is present). Stock has classic Mannlicher styling with steel nose cap, bail type front sling yoke, small right hand cheekpiece, and point pattern checkering at grip and forend. Toe line of stock behind horn grip cap is stamped "AUSTRIA" and with rack or registration number "34832". CONDITION: Excellent, retaining over 95% original factory blue with some thinning and silvering on sharp edges. Front action screw and trigger plate retain most of their original case hardening color, and bolt stop retains over 90% of its brilliant temper blue. Stock retains nearly all of what appears to be an original factory deluxe finish which is much shinier than that normally encountered on the standard Mannlicher. This finish has numerous knocks and scratches with a fair concentration of scratches on left side of butt. Bore is excellent, bright, sharp, and shiny. Action is smooth. A really classy Mannlicher. MGM11 Barrel Length: 20" Caliber/Bore: 8x56 Mannlicher Schoenauer FFL Status: Curio & Relic Manufacturer: Steyr Model: Bolt M1908 Serial Number: 12554

Photos:

The Antinit barrel and barrel rib were offered as 'cost options' in the 1939 Stoeger catalog (Antinit with rib was a deal!). Notice also the "stock of specially selected pretty wood" option: