I have compared RSI, Reloaders Archive, and JBM,Exbal and barnes. If the same atmosheric data and bullet info is used, they have all been within an inch of eachother. RSI and JBM lets you use differant drag models such as G1, G5 and G7. Relaoders archive lets you use a number in place of the G factor like for G1, you use .290 From there, its all about manipulating the drag model number or the G model along with the BC to equal your real world data. Barnes doesnt allow you to change barometric pressure or humidity, they are defaulted at the standard.