I have had good success using H335 in my .223. I understand that this powder was developed for the .223 round. I also use IMR 4064 and 4895 in the .223. I use the 4064 in my Garand and the 4895 in the 7mm-08.These three powders are close in burn rate and work quite well. I would like to try other powders but with these 3 I have a myriad of loads to work with.
I use IMR 3031, 25grs, with a 55gr sp and get really good results. Not too hot and plenty fast, unlike some of the gurus here ( nothing but respect guys, I mean it), I don't have a, a, crap I forgot the word, one of those things used to measure bullet speed. But, I fired a few at some four inch cedar posts and they blew the backside off. I mean, there was only half a post left. I got this load from the reloadind pages of M.D. Smith. Now, if you can only find powder.
I use 25 grains of IMR 3031 with 55 grain FMJ and soft points in my AR-15s. Always get flawless functioning and excellent accuracy with that load. Most folks overlook IMR 3031 when loading the .223. That is a mistake.
I have achieved sub 1/2" groups using H-335 and BL(C)-2 behind 69gr. Sierra BTHP Matchkings. My RRA has 1:8 twist bull stainless barrel and prefers the heavier bullets. I will also try Varget since it has proven to be the most accurate in my .308 AR and may provide good accuracy in the 5.56 as well. IMR3031 has always been my choice for my 30-30 loads and I have not tried it in the 5.56 yet. It is a superb powder for the 30-30.