I measured a couple batches of AN960 (one from ~1983 and one from last year from AS) and the NAS1149 washers supplied by Van's. The AN960s came in consistently 0.002-0.003" undersized at 0.060-0.061". The NAS1149 were 0.0063-0.0064". n=5 from each batch.
Interestingly I also have mixed in with the old batch of AN960s some washers that have a silver-colored plating (nickel?) and match the NAS washer thickness.