I actually love 40 cal but they seem to be a thing of the past. I’ve got 3-4 hand guns that shoot 40 cal & a lot of ammo but no one seems to be producing anything new in that caliber.
I carried a .45 caliber auto for years. Colt Combat Commander. At one time in my life, I actually carried 2 of them, one on each side, in a double shoulder holster. However, the recoil for a .45 is tough to deal with when you have to rapid-fire. The knockdown power is immense. Most of the Houston Police and Sheriff's here carry a 40 cal, the knock down power is very good, and the recoil is much less compared to a .45 cal. So I put the old .45 cals down and gave the .40 a try. We both had to rapid-fire fire getting certified and meet a criterion. Target distances were 3, 7, 10, 15, and 25 yards; we both usually train at 25 yards. Both of us easily passed, and my wife had no problem dealing with the recoil in rapid fire. I have been shooting since I was maybe 6 years old. Is it easy to control rapid-fire as a 9mm? No, but I have every bit of confidence that 1 center mass hit with a 40 cal will do the trick ( can't get a double tap off very accurately). I do have a MAC 10, Model – MI0A1, which weighs 6.26 pounds with no suppressor or the 40-round magazine. My S&W SD40 VE is 2.26lbs, so the difference in weight shooting 9mm, the MAC 10 has almost NO recoil. I can literally empty 40 rounds pretty accurately in seconds. I also have several other calibers in the house, 38 special, 32 mag, 25 auto, 22 long, and would have no problem defending myself with any one of them. I have quite a few rifles, but the range of these would be a problem where I live....223, 30-06, 30-30, 50cal, and Krag 30-40. Three shotguns, 20, 10, and 2, 12 gauge. The 20-gauge is a sawed-off double-barreled coach gun. I have shot this with one hand, pulling both triggers at once. gun. I keep a slug in one barrel and OO buckshot in the other. This will literally take a door down.