I don't show "CTC" on any list of government inspectors. A picture might help show if the letters are individually stamped or part of a made up stamp.

Those guns were declared surplus after the adoption of the M1911, and many were obtained or bought by other government agencies, private corporations, or individual citizens, any of whom might have marked the gun to indicate it was their property.

I could speculate on the meaning of the letters, but it would be pointless.

Jim