380 is a ball powder so it probably fits denser. 27 of Varget is more than full, compressed, crunchy. Not ideal, but it works.
If you popped a primer, you are pretty darn hot. Published max is a guide, not necessarily your goal. Your actual velocity is, yep, a guide, not your goal. I think I topped out at 24 with Varget under some 75 Amaxes. Varget (which I prefer to H4895 from 55 grains on up) has tended to run about a grain more than H4895 under the same bullet in the same rifle.
