As others have said, keep it lubed and shoot it. It appears to have improved as you shot it. If it still does it after a couple hundred rounds, then I would look at what else may be happening.
With possible exception of a RR LAR-8, this should work well.
https://www.larue.com/products/tacops-1-sniper-for-ar10/
If you buy it and it doesn't work, I will buy it from you for what you paid, including shipping to you and to me if needed.
I have first hand knowledge of @Rsquared and his attitude of the area. If you are anywhere close to his level, there must be something in the air around there that make y'all like that. It could be all of the BS flying out of the government bureaucracy. 🐄💩
I am sorry for your losses as well. I lost both of my parents in the last year and a half. It is difficult to move on at times because you want to pick up the phone to ask them a question that they would surely know the answer. As was said, honor your dad by doing something that he would have enjoyed with you. They live on in you and your actions.