chiming in very late here. For some cartridges and rifles and powders and bullets GRT is spot on for the Optimal barrel time and i can basically just grab a load straight from the simulation (in theory, dont do that!)
in others its way off. It may be coincidence but GRT for me always predicts well with large case sizes and n500 series powders but completely drops the ball with n130 n135 etc. I suspect this is due to it not being updated and those powders having shifted in burn rate etc a little since the last update.
In general i definitely find the OBT calculation to be mostly spot on, but it doesnt save too many components if you want to work safely since you will still be working up.
in others its way off. It may be coincidence but GRT for me always predicts well with large case sizes and n500 series powders but completely drops the ball with n130 n135 etc. I suspect this is due to it not being updated and those powders having shifted in burn rate etc a little since the last update.
In general i definitely find the OBT calculation to be mostly spot on, but it doesnt save too many components if you want to work safely since you will still be working up.


