The Berry's 124 gr. FP bullet is an excellent bullet for the 357 Sig round, though there are a couple of caveats. First, keep your velocities below roughly 1,250 fps. Second, don't overcrimp the case mouth.
I've loaded well over 10,000 of the Berry's 124 gr. FP bullets in 357 Sig, using the recommended charge of AA-9 powder. They are laser accurate out of both of my 357 Sig pistols. The AA-9 powder fills the case and is compressed, which helps greatly with bullet setback.
You don't want to over crimp the case mouths, or you'll cut the thin plating of the bullet. This causes the plating to come off in spots and is detrimental to accuracy.
There is also a third caveat: Don't load them with Power Pistol powder! A full (maximum) load of Power Pistol will cause them to tumble and hit the righthand upright of your chronograph........ The two that did fly straight enough to get a reading on the chronograph were going a little over 1,450 fps, which is way beyond the design limits of the plated bullets.
As for coming apart, that's balderdash. The only way a plated bullet comes apart is when it hits a hard object, either metal or concrete. I routinely drive plated bullets at 1,300 fps and they don't "come apart". They fly straight and true, but that is about the upper limit for them before they start to strip the rifling past that velocity. They are after all, pure lead bullets that have a thin covering of copper plating.
I also make it my own personal policy to only post my personal experiences, not what I read on the "internet". I also don't post loading data, period. And that's because it's way too easy to transpose numbers, mis-type, forget, etc. I also won't use data posted on forums, for the same reasons, but that's just me. I still get my data the old fashioned way, from reloading manuals, where it's been tested in a ballistics lab by professionals. I've been in the ballistics labs of both Sierra Bullets and Nosler Bullets, and know what goes into the testing of each and every load. There isn't any guessing there.
Whew, I feel better now............
Hope this helps.
Fred