I went and shot Glock's yesterday. I'm interested in buying either a G27 or G30. I was a little rusty on semi-auto shooting. Haven't been in almost a month now. However I was able to group my .45 rounds much better than the .40 rounds. Recoil on the .45 was much less. I haven't shot .40 in a long time, I have a XD45 but I'm going to sell it. This gun will be for conceal carry so thoughts on the variances in calibers and models would be helpful. Despite the grouping, which I'm sure with a little more practice I could accomplish with the .40 I couldn't tell much difference.