Raven, Ai was changed in the last few years, today "average" is a better shooter than the old "ace", so if you play old campaigns, you'll get your ass spanked every mission, thank to team daidalos.
Stick to campaigns written in 2013/2014 and you have more hope that campaign builders have taken the new sniping ability of AI into account.
Edit: you can also make another install, up to 4.09/4.10, and play older campaigns. Some thinks 4.09 was the most enjoyable version of the game, anyway. I don't, and prefer to play newer campaigns, but to each his own
