Have mostly tried AR-Comp in the .223/5.56, where it works pretty well, though I haven't gotten as much velocity as sometimes reported in my rifles. In the .308 I haven't found it outstanding.
If you can't find Varget, I would definitely try Reloder 15. I realize it also isn't very available right now, but as far as I can tell (after using it in several cartridges) is the same powder. Or at least it does exactly the same things in several cartridges, and is very available right now, due to Western Powders becoming the U.S. distributor for Norma powders a little over a year ago.
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