I probably don't need to explain to anyone here that more important than what gun you use, is caliber. Without arguing the merits of one caliber over another bring "enough caliber" to EASILY accomplish the objective. More important than caliber is gun, bring enough quality, maintained in such a way as you will Never hear "click" when you want to hear "BANG". And 7x more powerful than both of these is hitting the target, amazing but even if you have enough bullet, and enough gun the hard part is still hitting the target. That means you need to practice right and often. Real practice, means quality time with some sort of plan. Plinking is sorta practice, but unless you do it with the gun you'll use when the SHTF, or your carry gun for us CWP types, you are leaving the most important factor to chance. You must practice under various conditions, various ranges, with various targets, and vary your speed! The factor in any sort of gunfight you have least control of is WHEN and HOW LONG the engagement will last. Here's the thing, if you live in the city you probably can't practice outdoors, in the rain, at night, with a stiff crosswind. However if you expect to be attacked by a paper target, on lane 2 at 7 yards with the lights on,,, well you're probably ready and that .45acp Wilson Combat will absolutely do the job if you have factory ammo. But suppose your attackers aren't fiber based ink shapes? Maybe there's more than two, they have a pulse and can move and think, it's dark, cold and drizzling, the wind is blowing hard and thy are armed with pipes, chains and at least one gun... They are 30' away and you wish you stayed with the car on the highway.... Ok now you get where I'm comming from, here are some options and tips; Have a training plan for each session, know what you want to practice and how to do that. Vary your pace, sometimes practice each shot with controlled sight picture and breath control, and trigger squeeze... Sometimes 2 of 3, sometimes 1, sometimes push your limits and leave time for none of that. Carry the conditions, go to different ranges, under different conditions. I schedule my range sessions, weeks in advance just so I won't know what weather to expect. 98% humidity @100 degrees-F will put enough sweat in your eyes to make 100 yards shoot like 300, cold wet hands will take enough off your game to open your groups at any distance. Find a competitive lcal group and get involved, USPSA, IPSC, NRA, CMP and many others have formal and informal competitions everywhere and they are your best opportunities to challenge your limits and experience new conditions,under someone else's time table. My iron sight M16 at 100 yards is plain and simple too-easy, every shot will be in the black and almost all are going to be 10x, drop the temp to 50, with a gusts to 20mph from 2:00 with a slight sun shower well my upper limit with these conditions is about 200 yards with a few x's and mostly 9's and 10's. Shoot your favorite target pistol in low light with a beep and a clock ticking, then tell me how ready you are to engage 10 individual targets with 2 to the torso and 1 to the head, moving between cover and concealment for every 2nd target and your hits/time may disappoint you the first time, but I promise if you practice you'll be happier the 2nd, 3rd and 4th times you try this. Practice is great, even required, but TESTING tells you when you're ready. IMHO, Testing and training are much more valuable than unlimited ammo punched through paper at 15 yards. Good luck and let me know how you are "upping your game". Here are some links; International Practical Shooting Confederation The Civilian Marksmanship Program NRA Sports NRA Training NRA Membership Application There are many others but these are easy to get started with.