I use 50 grains with a WW case, WLR primer, and a Beartooth Bullets Piledriver Jr (actual weight 436 grains), get mid 1700s with great accuracy.

I've also used it with 300 grain bullets, taking them up to 2200 fps, again, good results in the accuracy department.

Like you, I have also found H4198 to be very, very accurate.