A week or so back was a thread about Gordons reloading tool and it's accuracy. I did some research on using the tool and not surprisingly you get out of it what you put into it. I weighed my rifle, contacted the manufacturer of the barrel and got it's true twist, length, and gas port diameter. I had to use a 120 SMK because the Barnes 120 MB was not in the database but over all the computed Optimum Barrel time was off by .02 gns to what I found in real life. GRT precited 28.72 and in real life I found my node at 28.7 gns of TAC. Apologies about the image size of pic 1 but I use a large monitor and it did not reduce well. I reduced it to 1920 wide, any smaller and the text quality suffered. Pic 1 is the GRT screenshot, pic 2 is of the Shot Marker target measured in Ontarget software. Chrono readings on the Ontarget picture were transferred from my ProChrono which was appx 12 feet from the muzzle