Meplate diameter of the LFN is .120 inch smaller than bullet diameter, .090 smaller for the WFN, FN and WLN. At 375 speeds I'd reccomend the LFN, as 1800 fps will be very easy to get with the 375 Win, and will be a slow idle for a 375 H&H, if that should be your chambering. If you have the longer cartridge, better send a throat slug with the order and give me the option of upping the weight so we fill it up a bit. Most of these have long funnel throats and need long bullets, fat enough toe fill the throat and chamber to perform well.