My experience with XTPs and expansion testing has been limited, but educational. The only .357 load I've tested was the 140gr. load, and it did not expand in water when fired from my 3" Model 65, but expanded a little from a 6" Security Six. Quite unimpressive, when compared to Gold Dot loads, or even the moderate velocity Golden Saber 125s. In .45 ACP, I've never gotten consistent expansion with XTPs, and usually, none at all. However, when I load XTPs in my .460 Rowland, they expand and fragment. It appears that the expansion threshold velocity is substantially higher than advertised for these bullets. (Keep in mind, water ain't flesh and bone, so your results may vary.) FWIW, I have always gotten great accuracy results with XTP bullets, in every loading I've tried.