My sources show an A.P. Casey, who used the letters APC. The only inspector I can find using the single letter C is too early for the SAA.
As I understand it, the Colt records mention only those details that differ from the standard. At that time, the standard would be .45 caliber, with wood grips and a 7 1/2" barrel, so in the absence of any notes to the contrary, that should have been the original configuration.
I would like to see sharp clear pictures of those frame and trigger guard serial numbers.