John in NM
I don't put too much stock in an amateur being off by 1 vs a manufacturer's numbers. The amateur tested 1-2 points on 1-2 chisels. The manufacturer *probably* used a statistically valid series of 100-300 samples and is reporting a mean value.

There could also be a great deal of variation just due to testing setups, calibration methods, judgement calls (significant in more complex tests), and just operator errors. But usually the biggest reason these are apples to oranges comparisons comes down to statistics. It would be interesting to hear what range the first three standard deviations cover in LV's testing. I bet that 1 RC point is in the first or second.