Guns: Big Bore, Small Pocket
I've used the S&W 642 as a pocket gun for awhile now, and it continues to do the job well. Notwithstanding the popularity of the Chief's Special design, gunmakers continue to roll out handguns that push the boundaries of the pocket gun envelope. Personally, I'm fine with .38 Special, but here's some brief thoughts on the big-bore pocket guns that I've tried:
AMT Backup .45
An interesting gun, and probably one of the smallest .45s you'll ever shoot. The sights are even more rudimentary than a typical pocket pistol - on most AMT Backups, there's no front notch, only two grooves that you line up on the target. Size is comparable to a Glock 26, although it's heavier due to the non-polymer frame.
The Backup, at least with full-power defense .45 loads, had relatively harsh recoil - the whole "big slow push" that you get from a 1911 doesn't apply to a 20-odd ounce handgun that you can't get a full grip on. Combine that with a long, heavy DA trigger pull, and you have a tough gun to shoot on the range. The Backup seems to have a spotty reliability record, but the example I shot was trustworthy. It still struck me as more of a curiosity than anything else.
The polymer-framed Kahrs have long occupied the upscale pocket 9mm market. If you couldn't afford a Rohrbaugh but wanted something a little more refined than a Kel-Tec, the Kahr PM9 was, and still is, a popular pick. The PM40 is essentially its bigger brother.
Overall, it was a fairly shootable package, although the recoil was snappy like most pocket guns. There are actual sights on the PM40, which is a huge deal on a dark target range (or in a dark alley, for that matter). What I didn't like when I shot my friend's PM40 was its tendency to stovepipe. I suppose these teething problems could be resolved with a little diligence, but it doesn't inspire confidence; that might be why my friend eventually sold his.
Charter Arms Bulldog
Like a lot of shooters, I wish the .44 Special was more popular. It's really a fairly practical revolver round - enough power to serve as a defense cartridge, a bigger diameter bullet than a .38, but moderate recoil. The mania over the .44 Magnum kind of took the wind out of the sails of the humble .44 Special. To this day, when I see the former and not the latter on sale in a gun shop, I have to shrug, since for most people the .44 Magnum is just too powerful to shoot regularly.
In terms of small revolvers, there are still a few .44 Special options available from the big-name revolver companies, but the Charter Arms Bulldog is the only .44 snub I've ever tried. It's inexpensive but fairly lightweight, coming in close to the bulk and weight of a K-frame snubbie. You might get away with toting this sucker in a large cargo pocket, but it'll never fit in a normal pair of slacks. In addition, there's the whole look and feel issue - if a S&W is a Toyota, the Charter Arms revolvers are like Kias. That is, they'll both get you where you're going, but the decades and decades of refinement on the S&W are noticeable in everything from the cylinder latch to the trigger.