just some thoughts from a guy who has carried a .45acp pistol for 10 years.
colt .45 autos: i've had three that wouldn't shoot a full mag (7 rounds) out of the box.
Sig P220, best damn handgun in .45acp i've ever had, shot, carried.
Para(noid)ordnance, too wide of a grip to be completely comfortable, also,have heard of some reliability problems.
Kimber, never owned one, heard it was good.
Glock, owned several, like the light weight, the G-30 is a small .45acp, good shooter, don't like the fact that it only has a trigger safety.
Springfield Armory. don't know, but want one.
Smith and Wesson. Another proven design. Not heard anything bad about the Smiths.
Ruger "P" series. had two, don't waste your $$$
Also, there is no such thing as "knock down power" this is a trumped up hollywood movie scenerio.
"for every action, there is an equal and oposite reaction"
if there was a true thing as "knock down power" then the shooter too would be on the ground.
the true term is "stopping power" which is a bullet, preferably a hollow point, spreading apart and tearing meat, that's stopping power.
Also, i don't mean to stomp on Packin-Heet's reply, but....
DO NOT RELY on a "high capacity" magazine to do your work for you.
you need to practice, practice, practice to be a good marksman. if a person relies on a lot of rounds to "stop" the bad guy instead of marksmanship, (controlled, placed, shot) then why not be a gang banger with a Tec-9?
Anyway, good luck on your quest. i hope you find a good, affordable, reliable handgun for yourself.
i do not mean to "rant" or "flame" anyone. this is just my two cents and it doesn't amount to a hill of beans.
colt, out.