Love the 21SF!!!
I had 30 rounds left in a box of .40, so I shot that at one target and then got another target and shot 30 rounds of .45 at that. The difference was remarkable. With the .40, all the shots were sprinkled around the bulls-eye and 9-ring, with one round in the 8-ring. With the .45, the bulls-eye was nearly obliterated with many rounds in the 9-ring and none in the 8-ring.
I also remembered that I recently discovered that I am left eye dominant, but shoot right handed. I have always shot right handed, but using my left eye for sighting. Today I used my right eye. With the .40 I did shoot a little better, but still blinked most of the times when the gun fired. With the .45 I also used my right eye and don't think I blinked at all, which may have contributed to better results.