Originally posted by Purpose
You are not supposed to shift into 1st while rolling. It is not a "drive" gear, but functions only to get you going. This driving habit has lead to this result.

I've downshifted into first while rolling since I bought the car and I've put over 100k on it personally. First shifts fine. I've even dropped it into first on tight corners and hairpins on the racetrack, no grinds. Shifting into first while the car is moving isn't the issue, usually it's ramming the gears and beating the synchros, or shifting from a rolling reverse into first (intentionally broke a tranny doing that)