So, today I took my circa 1996 Gen2.5 G26 (many, many thousands of rounds through it), and my new Gen4 G27 (and my first .40 ever) to my indoor range to see how the two compare - for me. My goal was not to compare 9mm target ammo to .40 target ammo, but 9mm carry ammo to .40 target ammo. Why? Because I remembered from previous experience that .40 and 9mm were very different in recoil impulse/energy, in target load strength ammo, but wondered if the same were true for my carry ammo. Here's my thoughts from today, YMMV: 1. 115 gr. 9mm target loads (WWB, Federal Champion) have far (15-25%-ish) less recoil than the lightest .40 target load (WWB, Federal Champion, TulAmmo). No surprise there! 2. 180 gr. .40 TulAmmo from Wallyworld is cheap, and it works just fine. It is also very mild recoiling ammo for .40. I did note some "sparks" when shooting it. 3. Speer Gold Dot 9mm 124gr. +P recoils pretty similarly for me to .40 regardless of .40 bullet weight. So, I now think that in my chosen carry-quality ammo, there isn't much difference in perceived recoil between the 9mm and the .40. That makes me feel more confident in carrying the .40 for self defense for controllablity, and follow-up shots. I have some .40 Federal HST in 165 and 180 coming on the big brown truck of happiness. When it gets here, I plan to compare them to the Speer Gold Dot 124 +P.