Questor, Though I agree with using 231 or BE, there are a lot of competition shooters that swear by Unique. All three powders burn dirty and all three can produce fine accuracy. The key to loading 45 ACPs is to apply the proper taper crimp. The slower the powder burn rate, the more critical the need for a firm crimp, else "position sensitive" issues will result in poor accuracy. With BE, you can get by with a very light crimp because it burns so fast. The much slower Unique requires a firm crimp for good ignition and uniform velocities.
Last week I put the finishing touches on a 1911 that I built. I test fired it from a bench rest with several lead and jacketed bullets for feeding, function, and accuracy. The gun shot well with all loads but the 200 gr SWCs (loaded with 5.0 gr Unique) were the best for accuracy. I did have to install a weaker recoil spring to get positive function. I didn't try 231 or BE but I'm sure they would shoot just fine too. The point is; blowing out the 10X ring with the Unique loads tells me they work pretty good with a 200 gr SWC.