Since January, I went through 4 pounds of Bullseye loading primarily for my M&P40. I'm very glad I cast my own bullets and reload, otherwise I would have probably written off this gun as simply "unshootable for me". I finally got used to the jump for good follow up shots and can finally put most of my shots rather than just my first shot through a 2" circle at 15 yards (most of the time). For a change, I've just picked up an 8 pound jug of Unique which should last me at least through the next year.
Both powders are quite forgiving in the mid range loading area[\I][\B]. +/- 0.2g isn't going to blow anything up and the trick is to load it up above the minimum level to where it doesn't leave sooty cases, blowback gases into your face or spray unburned powder all over the place. Bullseye is a finer powder with a higher nitroglycerine content which will eat up the Hornady Plastic powder hopper if left in there for any amount of time. It is also denser than Unique which is dangerous if you have a tendency to double charge 38/357 cases. It is also more economical in that you need 10-20% less powder than Unique to get the same muzzle velocity.
Unique is a good bulky powder which will easily let you know if you double charge a case. It is also a little lower pressure powder which will let you reach a higher max velocity than Bullseye, but not quite as high as Power Pistol. PP is great for max velocity, but you need way more powder per charge and you'll get a good muzzle blast and flash which may be annoying to you or others.
Red Dot and Clays are excellent for building up pressure without high velocity (recoil). They are great powders for low recoil loads, but shooters get into pressure troubles when trying to reach high velocities with these powders. I use Clays for a clean burning load when I want my 40 to feel like a 9mm.
Hodgdon Universal is similar in performance to Unique but more expensive and a bit cleaner burning and I have been told measures better than Unique although I have never had a problem with Unique.
