A couple things:
-is +P harder on the weapon than a 357mag? If so, how? If your revolver is chambered for .357, shooting 38+p shouldn't hurt it one bit. Right?
-so you're saying that a 38+p and 38non+p will perform the same, all other things being equal?
A quick check of some specs would seem to disprove that idea. For example, Win Super X's (from CheaperThanDirt.com) (I couldn't find the same grain weight in my 2 minutes of looking, but I think that kind of makes the point):
In 38non+p 110-Grain Silvertip Hollow Point
Muzzle Velocity: 945 fps
Muzzle Energy: 218 ft/lbs
In 38+p 125 Grain Silvertip Hollow Point
Muzzle Velocity: 945 fps
Muzzle Energy: 248 ft/lbs
The way I read that is you can throw more lead at the same speed and deliver a bigger punch using +p. Its not much more, but 10% is something.
With all that said, and if my assumption that +p doesn't harm a weapon chambered for 357, why not run +p's if their benefits appeal to you?
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Ummmmm...the TOPIC is "What can and what can't a .38 special do?" I don't seem to see a .357 mentioned in the topic.