2520 is slower burning than 2230 and 2460 which are the typical powders used in 223. 2520 is often used for match loads in the 62-80 gr range. You should consult the free AA load data and work up your own load for your own gun.
I have tried it in several bullets from 52gr to 75gr.
I do have one 55gr JSP load (27.0gr A2520) group that printed .42 MOA at 200 yds from an 18" bbl... it chrono'd at 2980 fps.
Most of the other accurate groups (I consider as 5 shots under 0.5 MOA at 200 yd) were 68-75gr projectiles.