Home Forums Hunting & Shooting Ask The Gunwriters Which 6.5 mm bullets are two diameter?

I recall reading about those two diameter 6.5 mm bullets, and if IIRC it did have something to do with the 264 Win. Mag.. While we're on the topic of 6.5 mm bullets; who was it that once made single diameter 6.5 mm bullets that were .263 diameter ? Speer comes to mind but my memory is pretty hazy.