The C3 has the same slide profile as a GSR Carry, what Highnoon lists as the GSR 4"
The GSR 5" is a "Government" sized 1911, the GSR Carry is a "Commander" sized 1911, and the C3 is what would be referred to a CCO, having a "Commander sized slide and barrel with an Officers size grip frame.
Government Model (Gov’t): This generally refers to any 5” 1911 in standard configuration, it has the full 5” barrel with bushing, (although some models do exist with the 5" bushing-less bull barrel) and full frame which will hold with modern magazines 8 rounds of ammunition.
Commander model: The original Commander model has a 4.25” bbl with bushing and full frame, several makers do not use the bushing barrel, but instead have a 4” bull barrel instead with a full frame, for Kimber this is the Pro model, and Springfield refers to it as the Champion.
CCO: This was the Concealed Carry Officers model since discontinued by Colt; this was the 4.25” upper from a Commander mated to the compact frame of the Officers model which with modern magazines hold 7 rounds. For Kimber this is the Compact model, several others make guns in this configuration or a similar variation and their nomenclature differs.
Officers: Originally this was a 3.5” barrel on a compact frame which is .5” shorter than the full frame of the Gov’t model and Commander. With modern magazines this will hold 7 rounds of ammunition. Springfield refers to this size as the “Compact” model.