I don't have any first hand knowledge, but have read that you will need lots of time in Addis Abba as you will have to go to the bowels of the airport and claim and have your firearm inspected. From what I have read it's easy going, but returning can be problem. The next thing that concerns me is Ethiopia has a lot of rebel action north of the airport. Currently, it's not a problem, but I would hate to be there when it does become a problem. However it looks like the tide is turning.
https://www.wsj.com/articles/ethiopian-government-repels-rebels-pledges-peace-talks-11642005374
