As the other posters have stated, H-414 is slower burning than A-2520, and while it can be used to load the .223 Remington, it is not optimal and there are many other powders better suited to that particular cartridge. I tried the H-414 in .223 Remington many years ago, and found that while the accuracy was pretty good, the velocity was quite low, around 2850 fps out of a 24 inch barrel. You just can't get enough powder in the case to raise the pressure enough to generate decent velocity. Even IMR-4064 was capable of comparable accuracy while pushing the 55 gr bullet 300 fps faster. So I guess, if H-414 is all you have, and you want to use some 55 gr bullets and primers (I would suggest magnum small rifle primers with H-414 I used RP-7 1/2), go ahead. Myself, I would save my primers brass and bullets for a more appropriate powder like Accurate 2015, 2200, 2230, 2460, 2520, Hodgdon H-322, 335, Benchmark, 4895, Varget, BL-C2, CFE-223, IMR-3031, 8208-XBR, 4895, 4064, Alliant Power Pro Varmint, 1200-R, Reloder 7, 10 or 15, Winchester 748, Ramshot Exterminator or TAC. (I left off the 4198's because I didn't have good results with them)
I don't have as much experience with bullets over 55 gr, as most of my rifles have had a 1 in 12" twist. Perhaps H-414 might be more useful with the heavies with a 1 in 7" twist rate.
