Springfield Mil-spec. It is reasonable in cost compared to other quality guns. The .45 gives you the stopping power for defense which allows for some error: if shot placement is too critical, I don';t consider it reliable enough for defense - and there's no guarantees with .45, either, just a better chance. As far as .44, if you mean .44 special, it's about the same as .45acp. But, if you mean .44 magnum, it's a very high probability of a one shot kill, but the flash and recoil is too much for most people to be ready for a follow-up shot. In addition, there is the risk of over-penetration. Let's also remember, defense is just that: in most jurisdictions the test is imminent threat to your life, or threat of serious bodily harm. That means the attack is immediate, if not already underway. No time for careful set-up of a shot, no aiming (you point rather than aim, anyway), no clever tricks. The round has to stop, NOW, and be ready for a follow up for the (likely) event that the attacker is not on the floor, or has a friend.