It will work. It will just stick out a little bite past the barrel.
The 7 shot Choate Tool Winchester SXP SX Pump Magazine Extension will be best with that length barrel.
9 (+4) Shot Model fits 24″ barrel or longer.
10 (+5) Shot Model fits 26″ barrel or longer.
According to the manufacturer the Choate Tool Winchester SXP SX Pump Magazine Extension 9 Round is 15" in length.
No, we do not currently carry any.
According to reviews on this site, you will have to remove the two dimples inside the factory magazine tube.
It should be compatible, with the modification of the factory magazine tube, that is described on this page.
According to reviews on this site, users had to remove the two dimples inside the factory magazine tube, to allow the added capacity to be utilized.
These extensions are only for 12 gauge Winchester SXP's.
Not necessarily, but it is always dependent on the skills and tools available to the user during installation. If you are questioning your ability to install, it may be best to have a gunsmith assist you.