I shoot Unique in the .380. 3.6 grains behind a 102 grain bullet is a maximum load. I shoot 4.0 grains behind a Hornady 90 grain XTP and get 100 percent function and good performance and accuracy from my Grendel. It shoots a bit over 900 fps which is not a real hot load, but should get the job done. Honestly, I don't carry the gun much, though, and don't shoot it much anymore. Been a while since I cranked out a box.
A load I'm tending toward on the theory that expansion inhibits penetration too much in this caliber is a cast 105 grain SWC sized to .357. I cast this from a Lee mold and it's intended for the .38 and shoots well in light .38 loads, but it's pretty awesome for the .380, perfect function due to the longish OAL and decent bullet nose shape. 3.6 grains of Unique behind this bullet gives 920 fps/197 ft lbs out of my tiny Grendel, pretty hot, accurate, and 100 percent functional. My thinking is that the SWC and heavier bullet will give better penetration and te flat nose will do a decent job (better than round nose, anyway) of tissue damage. I'm really not warm and fuzzy about the caliber due to the problems getting adequate penetration. I have some of these loads set back, had carried the hollowpoint load, but I'm beginning to swing to the idea that the SWC might be a better bullet in this caliber for defense. It's all speculation, though, not based on any personal penetration tests, just reading about the caliber. I reckon put the rounds in the boiler room and the JHP will do the job. If it don't, just put another in there until it does.

On the up side, the little Grendel is awefully easy to hide and carries 12 rounds at the ready with another magazine if needed. I carry the gun if the dress situation demands it.