I've shot the 17HMR in both a converted 77/22 Mag Ruger with a GM barrel and a H&R Handi, and haven't seen any splits, but then I have to admit I haven't examined every case. Necks were blackened, as you'd expect with a case shape like that. I've shot Federal, Remington, CCI & Hornady brands, but keep coming back to the Hornady brand. I think Remington is now made by Eley? but it is my understanding that all the rest come out of CCI. All are accurate, but the POI tends to be different, which is why I have tried to settle on one brand (if available). I've got a Handi HM2, which I have not used nearly as much, and other than the darkened neck, seems to not have any splits. Wierd, but I doubt that the neck issue would be brand related.