Varget is the response you'll get for a lot of cartridges now, including .223 Rem and 5.56 NATO. It sounds generic, but Varget works. It's main claim to fame is it's low temperature sensitivity. It's a good middle of the road powder and works for a lot of the common chamberings. If anything, the only negative thing about Varget is that it has had significant lot to lot variances in the past. I have not experienced this myself (and I buy a lot of Varget in 1lb cans), but I have read reports of this and from what reports have stated, this isn't an issue anymore.
Personally, I've only used IMR 4064 and Varget in .223 and 5.56 NATO. I do suggest a long drop tube if you plan on using extruded/stick powders to get it packed in nice, though. I use 25.0+ gr of Varget with a 77gr bullet for a 5.56 NATO pressure load and without a long drop tube, I'd have a lot of trouble packing that much powder in.
As far as your use of moly bullets, I suggest you don't mix moly and naked. Choose one and stick with it. It is very difficult to clean out all of the moly from the bore and this can affect accuracy if you shoot both moly and bare bullets.