Unique.
With one lot, I did a work up for 357 Magnum and 125gn JHP's. I worked up to 9.7 grains - the Speer #14 max with no problems. I settled on 9.2 grains as the "set" round, allowing for a good deal of "headroom" (with Unique, I like to leave a good deal of headroom because it meters crummy). 1315 f/s through a 3" bbl. Loaded n shot lots of them at 9.2.
The next lot of Unique, that same 9.2 grains delivered very flat primers and difficult case extraction. The day this happened I was without my chronograph, so I don't know the velocity. I pulled the remainder - 32 rounds. I then loaded a new small batch at 9.2, and . . . flattened primers again. No more of that.
I haven't loaded additional 357/125's with this lot of Unique. I'll probably load a few at 8.8 grains, and see how it goes.
Coincidentally, I started a load work up with this same lot today - 45 ACP / 230 JHP. Just loaded them; haven't shot them - but that's for another post as a 'range report' after the work up is complete.
I'm not a fan of Unique anyway. I have 1 3/4 #'s and can't wait to get rid of it. In fact, the last unopened # (same lot as the opened one) may get donated to my range club to be raffled off. But a discussion about Unique is for another post too
.