I've loaded up quite a few warm .40's and from a 6" barrel it's very capable no doubt. I've ran 180gr XTP's as fast as 1400 fps and 200gr as fast as 1300 fps (both JHP and WFNGC Beartooth). If that doesn't work for deer then there's something wrong!

However, that said I think the achilles hill of either warm .40 or warm 10mm is the bullets, that even the tougher ones (XTP and Gold Dot) are usually showing signs of fatigue and failure before you hit max velocity. Sometimes it's fun to max something out to see what it can do, but in this case backing a litte off max velocity might help out as it would cause the bullet to hold together better which in turn increases penetration.

One load I worked up that I like is 8.5gr of Longshot (8.0gr was max for years, worked up to 9gr in stock Glock bbl) under a 180gr XTP that from a bone stock Glock 23 runs right around 1200 fps and I've found it very accurate. It's powerful, not too fast for the bullet and the G23 is super easy to carry.

Someone mentioned 357 SIG, I took to loading it with actual .357" XTP bullets and from a 6" can run a 158gr XTP to 1450 fps and a 140gr XTP to 1550 fps.

I loaded for the 10mm for years but got out of it because the velocity you can get from a warm .40 isn't much different and the 40 eats less powder and costs less overall.