The CCO is an officer's frame and a commander's slide. I got this gun by accident, cause I had gone to my local gun dealer that I'd been going to for years to order a stainless Colt Commander. About a week later he calls and tells me it's in, so I proceed to pick it up and when I opened the box I saw CCO. He said he'd send it back and get me what I ordered, I said I'll take this one and he even gave me a discount for the inconvenience. Since the. He has offered to buy it back, but it's not leaving my family.