I was a bit dubious to the difference between these two rounds as when placed side-by-side they're not all that different, only about a mm or two. But on my last range outting, I packed 50 rounds of 38 spl and 50 rounds of 357 for my GP100. I really noticed the difference when I loaded 3 38s and 3 357s in the chamber, spun it and snapped the wheel closed and fired without knowing what was chambered. When I rotated from the 357 to the 38s I thought the gun had misfired. Accuracy was really about the same, making it a nice practice round as it's nearly half the price. But the 38s really do feel like cap-gun rounds by comparison. Though, I did notice that the 357 rounds I was using had a particularly pungent and fankly, FOUL, smell to them when fired. They were Federal Green/white box rounds. Whereas the cheap reloaded 38 spl were less odorous, though very smokey.