I have been working with the NOE 311 247 BLK/WISP boolit. Since its designed for subsonic it drops like a rock, and range estimation needs to be almost exact to hit something. Because of this I was thinking that a boat tail would help. What do you guys think of casting a boat tail gas check out of zinc that crimps onto the base of the boolit? I know that there have been boolits that are cast in multiple parts then assembled, and I know of zinc gas checks, but have never heard of a combination of the two. Let me know what you think.