I'm a dedicated cast bullet shooter, so I consider myself qualified to comment. (I never buy Lee moulds, BTW.) I assume you are talking about the TL309-230-5R mold.

Looking at the picture on the Midway site, it looks to me like a marketing trap set to catch unwary shooters. I don't like that ogive at all. It would have to be cast very hard to avoid slumping, which means that it will act like a solid on game - won't expand at all. Is the nose size properly fitted to these modern barrels? It looks like it's intended to ride on the lands, but modern barrels often don't have enough land area to provide support. Can it be loaded into a .300 BK case without having any lead exposed below the neck? It looks like it will have lube grooves exposed. Not that it can't work that way, but it'll be a dirt magnet, and will lap your barrel into a smoothbore if the ammunition isn't kept scrupulously clean.

Just playing about in Quickload, it seems that you might get it to 1600 fps from an 18" barrel with 18 grains of 4198. But to do it, you'd be up in the 48,000 psi range, which is very likely to cause slumping of the ogive, no matter how hard you cast it, making accuracy a faint hope. Also that's way too much pressure for a tumble lubed bullet. Moving back to a more reasonable pressure of 30,000 psi. 1400 fps seems more likely. Whether the tumble lube will stand up at that pressure is open to doubt, IMHO. Thinking about it a little more, it seems to me that it's intended for subsonic MV from the git-go. Cast of 20:1 lead/tin it might actually expand on meat at 1100 fps

If that boat-tail works at all, it'll be the first one ever.

My cynical gene says that they've done one production run of these, Blackout shooters (who are unlikely to be expert casters or cast shooters) will buy them but will be unable to get the bullet to work, and they'll fade away. It'll never be run again. Buy one and put it away. 25 years from now it'll be a rare collector's item.