Originally Posted by
Galbraith
The simple answer is to first get good quality training, and train often......then train some more with other peoples equipment(borrow/rent/buy). Once you think you have trained well and tried a wide variety of drills, then go find a different teacher and train with them(repeat even into old age). Study, and make it a passion to gain knowledge within the box, and outside the box of everything firearms related. Be open minded, but listen to ALL opinions with a grain of salt that needs further verification. After a while, your experiences begin to lead you in a direction that will best fit within your own strengths and weaknesses regardless of what the mainstream may be following at the moment.
All the major service calibers work if you do your part and your shots hit vital anatomy. It helps more if you use modern, good quality defensive ammunition. Many people favor the 9mm now days because it is generally easier for "most" people to target that vital anatomy, and if a shot fails to hit that anatomy, the 9mm's characteristics make it easier to try to hit it again, and again, and again......usually 15 to 18 chances before the gun stops going bang and it is time to stop pulling the trigger and perform a different task. With larger/stronger calibers that task can be more difficult, particularly if you must shoot single handed. These days I use .45acp on duty, and 9mm off duty. I have my reasons, but most importantly I can shoot my duty .45acp often better in meaningful, timed courses of fire than I can with other chambering in the same platform. It doesn't hurt that I get a decent supply of free .45acp training ammo. The simple physics of 9mm give me a "tad" faster splits in follow-ups, but my accuracy and groups are measurably better all the way beyond 50yrds. Other criteria for me are that I can also shoot the .45 quite well in courses of fire where I must shoot off-hand, or primary hand only. I am of course handicapped by having only 10+1 rounds on tap, but it makes me a very accomplished reloader compared to my 9mm counterparts. These are things that I determined after thousands of rounds of testing a particular platform and caliber, thousands more rounds in other tested calibers. What works for me, may not work for you. You have to dedicate yourself to getting the experience........the instruction, the practice, and the exposure to the topic.