Model 12 Standard Trap Forestock|Winchester Shotguns|Forum|Winchester Collector

I recently bought a model 12 “STANDARD TRAP” , as marked near the matching s/n’s.  It was made in 1931, 12 gauge.  The checkered butt stock, very nice walnut, looks like other checkered stocks I have seen on trap models.  The forestock however is what I would call the standard 7″ grooved version found on field guns, not the checkered extension forestock.  I wouldn’t think it left the factory that way.  If I can find an extension forestock (I will post in the swap and trade section), do I need to change out the magazine tube also? Looking at pictures from various sources all tubes appear to be the same length.