I've been hearing that for years, but have never had any issues, I started reloading over 50 years ago, I have never had any problems, 17 Remington thru 375 H&H, 13 different calibers come from a large family of hunters shooters I do all the reloading, nickel is harder than brass but softer thsn sizing dies, they require a little more effort than but if the case's are properly cleaned and lubed you are good to go,