They were machined from solid billets of steel rather than cast like the post 64's are.
They have controled round feeding rather than the push round feeding. Some consider this a plus.
The extractor is obviously much stronger than the small extractor on the post 64 rifles.
Parts were more precisely fitted to each other.
Quality control was much much better on pre 64 rifles.
The stocks were of much higher quality woods.
The bottom metal was machined from steel rather than aluminum alloy on the post 64's
I think alot of people would disagree with alot of that. I can't say any of it is undisputed fact exept the extractor differences.
I have seen outstanding Post64 and pre64 models. But then again, I wasn't shooting in 64, so really shouldn't even be posting on it. But it made me think of a John Barshness article where he talked about this very issue. He said he didn't understand people looking down on the post either.
And shoot james has been around since the 30-06 came out
. He seems to not mind the Post64's.