I've gotten low readings with JSG every time I've chronoed it GM54-120. It's made no difference whether I was shooting conicals, sabots, or balls, heavy bullets or light, or whether I seated it hard or just touching the powder. However, it was the cleanest powder of them all by a significant amount. Except for the cost, I would use it for target shooting. But in my opinion it's way overpriced for what it is.