Various bullets are created for a certain velocity bracket and may behave differently out side of that bracket. We can't depend of simply interpolating data from the results of one test or another into data for another round and another speed altogether.
The deep and wide hollow point 135 gr. bullet was developed especitally for the speeds encountered by those carrying .38 snubbies. They perform well in that bracket - adequate if not spectacularly.
There have been numerous reports of the speeds generated with .357 ammo having adverse effects on that particular bullet. Although it seems to penetrate at least as good as the .38 rendition, some fragmentation and over mushrooming has been observed in private testing.
I used to carry the round myself. I contacted Speer and asked them about the reports. If you'll allow me a rough but accurate PARAPHRASE I'll tell you their response directly to me.
"The 135 gr. bullet used in the .357 ammo was developed for the .38 spl. short barrels. When fired as .357 ammo it is indeed being 'overdriven' and may loose it's tip. However, being a bonded bullet, it should hold together and continue to penetrate. The .357 135gr. for short barrel ammo should be a good ammo for you to carry in your snub barreled gun."
"Over driven"? "Lose it's tip"? "Should hold together and continue to penetrate"?
I was not reassured. I have switched to the DPX round for similar recoil and more dependable performance in a .357 round.
I suppose the .357 Speer is just fine for carry in a snub. I just trust a bullet that was created for the velocity threshold that is being generated in my particular gun more than one that has some question marks concerning it.
Not to tell you that you are not packing OK ammo. Just pointing out that we cannot just boost velocity and expect that only good things will follow from it.
I like to see actual tests for ammo I carry. I have seen it for the .38 spl. Speer short barrel stuff. It performs fairly close to FBI standards and just fine for civilian carry IMO. I have seen tests for the DPX round that I carry in my own gun. I have not seen tests for the .357 Speer short barrel stuff.
Just pointing out that there may be a number of reasons why a person would choose the .38 spl. rendition over the .357 stuff - recoil generation being a legitimate reason among several other reasons. Also there are a number of reasons for choosing other brands of .357 rounds over it as well IMO.
To each his own, I suppose. But you can't win when saying that people who choose the .38 spl. round have used faulty reasoning. They may well be reasoning just fine.