G'day, Eric.

Per the 1939 Stoeger Catalog (touted as 'sole importer of MS rifles and carbines to the U.S), "Upon special order and at an extra charge, the following special work can be carried out by the factory:
Extra long barrel, up to 23 inches, caliber 6.5 m/m........ $15.00
Extra long barrel, up to 24 inches, caliber 8.2 m/m........ 15.00
Extra long barrel, up to 25 inches, caliber 9 m/m........ 15.00
Extra long barrel, up to 26 inches, caliber 9.5 m/m........ 15.00
Sight protector............................................ 1.00
Stock of specially selected pretty wood.................... 20.00
Stock specifications differing from standard............... 15.00
Full stock in rifles which normally have half stock........ 10.00
Horn cap at the muzzle of sporter type..................... 8.00
Telescope mount and shooting in, exclusive of cost of 'scope ( see pages 238-241 and add cost of desired telescope)
Special testing or shooting in with foreign ammunition...... 35.00
Extra for rib............................................... 35.00
Antinit without rib......................................... 30.00
Antinit with rib............................................ 45.00
Special folding peep sight.................................. 12.00
Takedown model extra........................................ 15.00
Extra light rifles (not for high speed rifles).............. 25.00"

It seems that as of 1939, one could order a 1910 with a barrel 'up to 26 inches' (+$15.00), 'stock specifications differing from standard' (+$15.00), and / or 'full stock in rifles which normally have half stock' (+$10.00).

Rather accommodating, they were.

I'd post scans of the relevant catalog pages, but have had no success in previous attempts to do so.

BR.