There is another thread on Frank Hamer and the movie that just came out that was started about 2 days ago. What I have read is that one of the other men with Frank Hamer shot Clyde in the head with the model 8 he had in 35 Remington. He fired before Frank Hamer gave the signal to fire at Bonnie and Clyde. Here is the link to one of several stories I have seen saying that Prentis Oakley shot Clyde with a model 8 in 35 remington.
Another story about the ambush with some pictures.