The particular bullets I'm working with, are sized .356. A few years ago, I bought some that were sized .357, and in the pistol I was trying to use them in, at the time were more accurate than .356, but, I could only load the .357 bullets in Federal brass, otherwise, I couldn't get them in my Wilson case gauge.
I'm getting 1"-1 1/2" groups out of the same brand of bullet, in 147 grain, at 25 yards, out of both of my Xfives. Even though the 160 grain bullets aren't as accurate out of my pistols, they shoot softer. I've been having issues with my hands, and haven't been able to shoot limited, or single stack, with major loads in the last few years.
I actually talked to the bullet manufacturer and his first thought was that I had too much crimp. I told him that I don't have any crimp. I'm using once-fired Winchester brass and measured every case for length and have my die set to just straighten the bell. His next suggestion was to switch to Sport Pistol, but, at around 830 fps, I still get tumbling out of 3 different pistols.
I guess that I'll just use up what I have left at local matches, running them at 800 fps. I won't take them to a major match without more cushion than that.
That said, this thread is about Sport Pistol powder, and I'm REALLY impressed with it. It meters well, is softer, and more accurate than VV310, and when at the chronograph almost all are duplicate readings. I assume the few that are a little lower, or higher are because, according to my scale, the bullets don't always weigh out exactly the same. One of these days, I'll try some Zero, or Hornadays which I've found to be consistent.