OK, I'm trying to understand if there are bullets out there that can harm the regulation of a double. I have a Heym 88B in 375 H&H and I was looking at the Barnes TSX in 350 grain for an upcoming Buffalo and Hippo hunt. I have read before possibly some inaccurate information that said only use lead core bullets in a double. Please help explain if this is current information based on doubles built today. Thanks in advance.