He's 6 years old and easily reads 3-4 chapter books a day on the weekend... Boxcar Children, etc. His comprehension is perfect. But I guess he must be reading quickly and guessing some as he reads.
Angie, he may be reading from context when he reads to himself. I've been told by reading professionals that reading aloud is slower and more prone to error for everyone (even adults

).
When he reads the books to us he'll sometimes mumble words or he'll skip words or he'll read "he's" and say "he is"... really just silly mistakes.
I think this is really common for young readers, and wouldn't worry about this unless he's doing things like having difficulty with simple words that you know he knows, or not seeming to recognize letters and sound correspondences that you know he knows.
We notice it and then focus on it for a week or two and he gets better. But he gets annoyed when we correct him over and over again and it does make bedtime a little less fun because we can't really get into the story.
I wouldn't worry about having him read out loud at all if he doesn't want to at home. He'll most likely have practice at school. Our teachers always recommended that the most important thing parents can do at home for their children in elementary school was to read *to* them - no matter how well their children read or how old their children were.
Best wishes,
polarbear