If it has a bull barrel like the STI website says it does it is not SS legal.
Prohibited modifications and features •External modifications or features such
as weights or devices to control or
reduce recoil (such as, but not limited to,
thumb rests or components which could
be used as such).
•Coned barrels, bull barrels, or barrels
with flanges, except in 1911 compact
pistols with a barrel length of 4.20 inches
or less. (Note: All other barrels must
have barrel bushings and conform to
factory profile).
•Slide lightening, cuts, ports, or any
milling deemed to provide a competitive
advantage