I loaded up some 53gr TSX in my .223 (ruger 77Mk II)and my dads .223 (contender rifle) I went 1gr over the max for the standard 53gr x bullet and my rifle had a 2" group at 100 yards and my dads had a 3" group at 100 yards. I also loaded some with 1.5gr over max for the standardx bullet and my rifle shot a 1" group with two holes under .5" andI shot a .8" group withmy dads rifle. You would not think that .5 grain would drop the group size that much but it did. I am going to add another .5gr to mine and see if it brings the group a little tighter. Over all I am happy with there accuracy.

I have had the same experince with 223,22-250 and the 220 Swift. With the 223 being such a small case, a 1/2 grain of powder can make a huge difference in accuracy and even amoderately warm load and one that peirces primers.

What powder did you use?

H335 for the TSX and for the partitions I tried H335 and AA 2460