Choosing the right PFI scope starts with the caliber and then, the barrel length of the rifle. Thereafter, choosing the appropriate bullet weight(s) will complete the pairing. Each optic model has a unique reticle that will provide data for a specific but common ammunition and weapon systems. Although each system is different, there are acceptable ranges of deviation for each of variables. This information is provided for each optic and caliber. If this information isn’t listed, please contact us, and we will gladly run the ballistic data and provide you with our best recommendations.