The 3 million figure is surely Kleck's.
The CDC report we are talking about here is NOT some kind of study. The CDC is prohibited from studying gun violence by the NRA. All the CDC can do is comment on what other people are reporting.
You are claiming the CDC supports the conclusion of 500,000 to 3,000,000 defensive gun uses per year, based on the report that it issued to president Obama in July 2013. The CDC has made no such claims, and it has conducted NO study into this matter. Indeed, the CDC is prevented from conducting such studies by the NRA, and this is not about to change anytime soon:
Republicans Say No to CDC Gun Violence Research
President Obama requested, in January 2013, a report from the CDC on gun violence. The CDC complied with that request with a report in July 2013. Six months is not sufficient time in which to plan, conduct, and publish the results of any national study of gun violence. All that the CDC's report to the president says it that some studies have claimed 500,000 to 3,000,000 defensive gun uses per year and that these claims deserve to be investigated (which, again, the CDC cannot do, because the NRA is afraid of what it would find).