Sevens, when you say it meters too poorly, what do you mean?
When we say "meters poorly" (and btw, Unique is almost always associated with this in any thread!
) it means that the powder is typically flaky or in large chunks (like IMR 800X) and it doesn't reliably drop from a powder measure with a consistency as well as tiny flake powders (like Titegroup, Power Pistol) or spherical powders (like W231, AA#7)
The end result is that when you use a mechanical measure to dump a set charge, the actual weight of the powder in each drop tends to vary a bit more than with a better metering
powder. This problem is magnified with a smaller charge weight. I.E., if you are making .44 Mag loads with 9 grains of Unique, it's often not as big an issue than if you were making 4 grain loads of Unique for .380 Auto.
Obviously, one of the keys to accuracy in handguns is a consistent powder charge. If you set up a powder measure to dump a charge of Power Pistol across 20 pieces of brass, you could dispense them and then weigh each piece to find them all within a tenth of a grain of each other, and out of my Lyman 55, even less than a tenth of a grain.
If you meter out a similar weight of Unique through your measure, you may find over 20 pieces that you have a fluctuation of 0.2 or 0.3 grains in weight because the powder doesn't meter well, and measure & dump as smoothly.
The other relevant thing I'd mention when you noticed that your premium defense ammo seemed to be more accurate. It's my opinion that if you want to do the MOST for accuracy in handgun loads, your best bet in one single item is to find an accurate bullet, or a bullet that your handgun likes.
Every thing you do to promote piece-to-piece consistency
will give you the most potential reward in accuracy, but I don't think anything we can do or any powder we can choose will do more than finding the best bullet for accuracy.
The best bullet is a compromise of performance & price. (for me, anyway!)