Nope it was a timing issue. I suggested a new op rod spring becuase if it is weak you may replace worn parts and still have issue and you will be chasing your tail looking for the problem
Atleast pull the op rod spring and measure it. It should be free of kinks or bends , no flat/worn spots and measure between 19"- 20"1/4 . If it isnt in spec replace it.
My rifle did the same thing, it drove me nuts trying to figure it out. I inspected every part and couldnt see anything out of spec. Rifle even went back to CMP ,they sent it back supposeably fixed and it still malfunctioned.
I put it away and forgot about it. One day I was looking at it and I saw the ear on the follower rod had a very slight bend in it. It was just enough to throw off timing.
Moral of the story is inspect all the internals "very carefully" and then look at them again. Check for anything that looks worn or "bent"
It very well could be the spring since rifle malfunctions halfway through the enbloc. As the enbloc emptys there is less pressure pushing up on it. If spring is weak this will only make it worse
Just my 2 cents
