.38 9mm Everyone should own at least one 22 LR. They are cheap to shoot and a lot of fun. It's all I shoot these days but I still have a S&W Model 10 in .38 that has had thousands of rounds through it. For almost 50 years I've been shooting revolvers competitively. Mostly USPSA Matches and ICORE. Many times at USPSA I'd be the only revolver shooter. Didn't matter I was always there for fun and to beat my times. I must have loaded a few hundred thousand rounds of .38s so it's got to be one of my favorites. 9 mm ranks high because that's what I carry now. It's also what I shot in revolver for the past few years shooting a S&W 929. Now I shoot a S&W EZ9. I still have a couple thousand rounds of 9s so I'm not worried about finding any on the shelf.