I really don't know, but it seems to me it was done simply to get more power behind a smaller load, for a faster, more accurate bullet.
I'm an old timer. When I started shooting expanding bullets was a brand new concept. So a big round like a .45 was a man stopper, and a military ball 9mm fared poorly. I am slow to change. So I tend to dismiss 9mm rounds as inadequate, even though the modern bullet designs have gone a long way to minimizing the differences between a higher speed 9mm and a slow, lumbering .45. So I like big bullets. I like proven bullets (like a .357).
Also there are a lot of military people out there and they like the .45 because they are not permitted to use expanding bullets. A 9mm ball bullet, I think most people will agree, is not a proven man-stopper (though it kills pretty well). A .45 in military ball is still an effective round.
I think that you will find that guys that have been shooting a long time gravitate to .45s and .357s and other major calibers. And those that are up on the latest and most effective bullet designs are happier with 9mm rounds and .380s.
So first you have to pick the demographic for your advisor, then listen to the advice.
Our boys in the military have been using the .45 ACP since before WWI, and continued to use it throughout WWII, Korea, and Viet Nam.
It was replaced by the 9mm, which has probably taken more lives than any other pistol round, if you count all the executions by the Nazis and tin-pot dictators. As for the police leaving it in favor of .40's, that was a backlash caused by it's failure in the big Florida shootout, in the 80's, and its deficiencies from that era have since been corrected by improved bullet design that makes 9mm self defense ammo compare very favorably to the .40 S&W.
9mm. not because its my favorite round, but because its easy to afford to shoot it a ton. I think there is no substitute knowing you weapon, and the only way to do that is to shoot it. id rather be up against someone with a .50 cal desert eagle that has only shot it twenty times than someone whith a .22 revolver who has shot it thousands and thousands of times.
but i think i'll stick with my HK45.
The 40;45; and 9mm are all great catridges. Look at their popularity, with 9mm being the most popular in the US and worldwide. The 40 is a heavier more powerful round and leaves bigger holes. Many police agencies are going to 45's over 40's for the penetration through auto glass and auto bodies, however slight. Neither the 40 or 45 beat out the 9mm 147's by much in this category. As far as what I've read the agencies who have adopted the new 147's have had very positve results in the one shot stop category as well as the venerable 124+P Goldots. I've shot Golddots for many years and I truly believe I sure the hell wouldn't want to be shot by one. Law enforcement has a very high priority concerning shooting into cars, not so much as for the average joe and the need for self defense against human targets w/o having to go through cars. All things being equal 9mm has less recoil, holds more bb's and practically does as well as either 40 or 45 even through cars. I likewise believe the 9mm to be more reliable in semi-autos due to it's size and shape, the 9mm is at home in full size service weapons to pocket pistols and cost's less. In all the ammo testing videos and articles I've read coupled with the 9mm's popularity and track record and for what I need it for the 9 will do just fine new or old shooter alike, however, I do like the 40 and 45 as well. Just my 2 cents, just shoot what you like, it's your choice.
Have a nice day and thanks for all the gun info!
I am somewhat out of my element in these auto loader topics, but I'd advise you to get any caliber and get profieient with that gun/caliber before giving any consideration to carrying a gun for social purposes. After that, get whatever you feel comfortable with.
We're getting rain here......lots of rain. But not so much at one time as to pose flooding problems.
There you have it... pros and cons, dos and donts. Personnaly I prefer the 9mm, for capacity and recovery. If i feel the need for more punch, Ill take my .45
Ive heard .45 too slow, but I havent heard of anyone outrunning one yet! 9's are cheaper, and with a 147g jhp, if you HAD to shoot someone, I dont think they'll be able to tell you the difference. Just my take
If someone handed me a 9mm and told me to go defend myself, I'd say okay.