I was going to use the JBM Trajectory system and feed in the data.But they dont have the hornady 300 Win Mag as a caliber.He uses a Hornady 300 Win mag SST 180 gr.The rifle is a Ruger American 24 " barrel.Usually he has a 200 yard zero.Any help.
Not understanding your question. 300 Win Mag uses a .308 caliber bullet. I went to the JBM site, scrolled through the drop down and see the Hornady 0.308 cal 180gr SST.