Another innovation present in the Citori 725 is the new Invector DS choke system, the DS meaning double seal. The unthreaded end of the choke tubes features a brass alloy band that prevents any choke tube loosening and keeps the outer wall of the choke tubes cleaner from blow-around. You can feel the additional torque needed when you screw in these tubes.
The lower barrel measures .738 in. via Skeets bore gauge, the upper barrel at .739. The exit diameters of the Invector DS choke tubes were a bit puzzling. The IC tube measures .739, the Mod .731, and the Full at .702 inch. Yes, you read that correctly: the choke tube etched “Imp. Cylinder – Lead / Mod. Steel” has essentially no constriction at all. At best, in the lower (slightly tighter) barrel, you have .001 in., .007 in. and .036 in. constrictions, the “Full” choke designated as a lead-only choke. Mis-marked factory choke tubes are a common issue and unfortunately this Citori 725 did not come with a useable pair of hunting chokes, a glaring oversight. As to what choke tubes are supposed to be, refer to "Shotgun Chokes" on the Tables, Charts and Lists page. Only the lead-only "Full" choke supplied comes anywhere close, the Modified choke does not even offer Improved Cylinder constriction parameters.