The fact is, few people are going to shoot 10,000 rounds through a sub-1-pound snubbie anyway. I have every bit of confidence in the durability of the Airweight with hot .38s in it. It's a well-made gun. But the reality is, nobody outside of Smith and Wesson's R&D department is probably ever going to shoot enough rounds through it to find out
exactly how long it lasts.
Is a .357 frame stronger? Sure. But if that was
all you cared about, you could get a 627, a .357 N-frame, and shoot .38 target loads through it. It weighs as much as a Super Blackhawk, but what the hell.
Is a .600 Nitro Express a more powerful stopper than a .357 Magnum? Sure.
I think you get my drift...
ALL firearms, and all mechanical devices, are engineered as compromises between a number of conflicting factors. You can get NASCAR-style performance from a Detroit V-8 engine. For 500 miles or so. That same V-8 will take your loaded work truck 200,000 miles or more without major maintenance, but it won't be set up to top 200 MPH on straightaways. TANSTAAFL.
The J-frame Airweight with hot .38 Special +P happends to hit the "sweet spot" for a lot of people, including me. They're hardly free, but they're not north of $700 either. They aren't fun to shoot 150 rounds of full-power loads though, but they're totally manageable guns.
I drove into the foothills yesterday, hiked up to the mountains, climbed up over the city and enjoyed a panoramic view of all of Southwestern Idaho. I had a 642 stashed in a very simple IWB holster, loaded with alternating snake shot and Cor-Bon rounds, a speedloader of snake shot and a speedloader of Cor-Bons. No sweat. Didn't weigh my down or get in my way at all, and I kept on wearing the same gun when I went to the store on the way home.
Would a 629 have been more powerful? Yeah. Would a NAA .22LR Mini-Revolver been even easier to carry? Sure.
The 642, though, has
enough oomph, but doesn't weigh me down much more than the Mini.
That's why the things are so damned popular.