Your problem is due to firing 38 specials, which I assume were not jacketed. With the 38 special being shorter then the 357's a lead ring is applied to the mouth of each cylinder. It's enough to keep the 357's from going all the way into the cylinders. A good cleaning with a brass brush will cure the problem.
No, I own a S&W .357, but I've never tried the .38 load in it.
Yes, I know it can fire the round.
I'm just shocked to hear about a S&W failure. I've never had a problem with any of their products.
Now, Taurus on the other hand...