I have not yet figured out how to get an AR-15 into my cargo shorts front pants pocket no matter how hard I try for three seasons tucked in T-Shirt weather.
I have carried and been paid to use S&W, Glock, Colt, SIG, and HK guns ever since 1975 and occasionally snuck a Walther or Beretta in here and there as needed. Nothing is superior to a Glock for simply going bang and hitting your target with no firearms related fuss.
As to a pocket gun, Kahr, Taurus, KelTec, and Diamondback products have been tried and passed to the junk pile as unreliable. My S&W M&P 340 .357 with Speer GD 135+P loads gets the nod whenever a Glock doesn't find a belt holster to ride on. They both go bang every time.
As to the AR-15, I'm only half joking. Surprise, time, and distance keep you alive. Anything other than nailing the threat from surprise from the longest possible distance away taking all the time you need means you are in the threats environment playing his game. Odds being what odds are and Mr. Murphy being closely related to Mrs. Murphy who is a cold be'ach, playing someone else's game means you lose sometimes.
No body in their right mind faced off in the street in Tombstone with pistols. They shot the threat in the back with a rifle as he rode into town. Dry Gulching means careful survivorship.