Is that the nose-pour, or the later base-pour, version of the Matthews bullet.   There were problems with the original nosepour version. As I recall the blocks Lyman used were too small and tended to warp. Production was pretty limited and as soon as Lyman found out about the problem they discontinued it and redesigned it into a conventional base pour in larger blocks.

I have both, and I shot that bullet In ASSRA 200 yd BR for a couple years breech-seating out of a light-weight sporter-barrelled  Miroku Brown- chester. (It is factory built with a fast twist Badger barrel during the run up to the BPCR and Creedmoor rifles).  That bullet WAS specifically designed for a fast twist barrel.
But I saw the light (got tired of seeing stars) and switched to a 38-55 highwall. 
  I had B&D rescale that same tapered design for the 38-55 and later for a 40-70SS project.  Personally I like that bullet a lot, though I have not used it for a couple years