Steel FRICTION RING, not steel shot.No steel in a full choke Model 11!!!
The muzzle is thin, and the steel was softer back when that gun was made.
It didn't need to be thicker & harder then becasue steel shot hadn't even been thought of yet.
Steel shot won't pattern worth a darn in a full choke anyway.
A MOD gives Full choke pattern.
An IC gives a Mod pattern.
rc