Varget is too slow for bullets in the 50gr range, save that stuff for 65gr or 69gr, get some Benchmark or something around that burning range. I agree that you wont be able to fit enough varget to cause any harm, I remember getting compressed loads with 69SMK at a little under 27gr with no pressure issues, in standard 223.
I've got a poly twist black hole Weaponry barrel that I have thrown the reloading books out on. I started HBN lubing bullets and adding powder until I saw problems, and I almost never saw problems...
I just copied and paisted these numbers from the electric notepad as some backup notes.
"223 HBN...53 TSX 26.9gr H322, 50 Vmax 26.4gr H322, 65 SGK 26.4gr Benchmark or more."
Way way way outside of published data! But these are HBN lubed and shot through a polygonal twist barrel, everything is keeping pressure low. 53 TSX lab radared at 3330fps from a 16" AR and the primers show little pressure signs.
I've been slacking, I've been meaning to test the HBN in my 260AI 30" barrel but I haven't got around to it.