Varget is great stuff. I use it for .223, .22-250, .308 Win, 6mm BR Norma, and lightweight Varmint bullets in .270 Win. It is usually one, if not THE, most accurate powders I've used in each cartridge, and it isn't temperature sensitive.
For .223, using Win, IMI, LC, or IMR (Guat 5.56) brass I have no real issues, other than it doesn't meter as well as, say H335 or TAC. It shoots very well though. I tend to load it for my bolt guns, weighing on a Chargemaster. But for an AR, 335 or TAC (for heavier bullets) might be better on a progressive press.
In .223, I like 26 Gr. Varget in Win or IMR brass, loaded either magazine length or longer, with 69 Gr. SMK and CCI BR4 primers. This shoots very well in both my AR and Bolt rifles.