I agree with GatorFarmer--the issue with +P would most likely be accelerated wear, not an exploding gun.
The Standard Catalog mentions a test run of 442's built for the Secret Service on the same frame as the no-dash models, with a lightweight alloy cylinder instead of steel. In theory those test guns would not have been as strong as a steel-cylinder standard model, yet they survived testing to 5,000 rounds using +P ammo with no failures. Knowing that, I'm not surprised that many people feel comfortable shooting +P ammo in their no-dash 442's, especially in limited amounts.
I shoot only standard-pressure ammo in mine, though. I find that it's more controllable, which allows me to place follow-up shots faster and more accurately. My favorite ammo is the discontinued 125gr Nyclad hollowpoint, but there are several other suitable defensive rounds currently available, including a standard-pressure 158gr LSWCHP from Buffalo Bore.