I don't use them for F-Class but I do use them for my Chicken, Pig and Turkey load shooting silhouette. I use 142 SMK for Rams. Compared to all the BR loads mine are powder puff. I use 32gr of Varget with mine for 2500 fps. Light recoil a bit more than a .223 for easy shooting a hundred to two hundred in a day. Turkeys are 420 yards away and the 123's shoot fine in the wind even going slow. Good enough for my offhand needs at least, one bullet strike on steel on top of the other over and over.
I would think the heavier bullet would outperform the 123 but it is a very good bullet in the 6.5
I would think the heavier bullet would outperform the 123 but it is a very good bullet in the 6.5