There is no comparison between the two bullets as far as copper fouling is concerned.With the tsx copper fouling is virtually non existant,if anything,even less than with nosler bullets.I also find the tsx much more accurate in my rifles and they produce more velocity before showing pressure signs.On game,the tsxexpands more reliably and does not shedit's petals as easily,due to a redesigned nose cavity.The xlcs do not copper foul,but they are no more accurate than the standard x in my guns.They perform the same as the regular x on game.