Lyman Modern Bullet Shapes
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Lyman Handbook of Cast Bullets, 1958

Lyman Modern Bullet Shapes

Do mould #s refer to as cast diameter or sized diameter? (43d Lyman Reloading Handbook)
   The first three digits of the mould number are the diameter that the bullet is to be sized to. The mould will cast a bullet from .001 to .003 larger to allow for sizing.Undersized bullets (mould number contains "U") must be used to size to .308 or other bore diameters. An undersize mould will cast a bullet approximately .002 smaller than standard moulds.

  For an explanation of the better theoretical benefit of a rounded nose, compared to a pointed nose, look up "New Exact Small Arms Ballistics" by Art Pejsa. In short, as the mose becomes blunter, the Center of Precession moves back towards the Center of Gravity. Obviously, a wadcutter has great potential accuracy, but not so great BC. The calculation of Cp is too advanced for the book, and is not included. Pity.
Epicyclic Swerve
   The perfect aerodynamic lines of this bullet make it potentially, at least, the most accurate of all. But it lacks the inherent stability of somewhat blunter shapes. And to become stabilized it often needs higher velocity than would be required with a blunt bullet.

Round Nose
   First step toward greater accuracy is a rounding of the bullet nose. This moves back the center of gravity, making for increased stability and considerably improving flight characteristics. Relatively blunt cast bullets generally give you best results.

   Here, the heel or base of the bullet is somewhat smaller in diameter than the forward bands, which are made to fit the bore. The heel fits into the cartridge neck. Bullets of this kind are not ordinarily sized at all but are shot as they came from the mould.

Wad Cutter
   A clean hole in paper targets was the original objective of these bullets. But their blunt silhouette seems to make them easier to stabilize and for that reason many feel they are more accurate. They also generate more shocking power upon impact and score clean kills.

Hollow Base
   The historic Minie ball was the ancestor of the modern hollow-base bullet. The explosion of the powder charge expands the bullet’s hollow base against the rifling. Only those bullets especially designed as hollow-base bullets are available in hollow-base style.

Hollow Point
   These bullets expand on contact, causing greatly increased damage to tissue, more sever shocking power, and quicker, cleaner, kills. Accuracy of these bullets also makes them popular among benchresters. Practically any bullet design is available in hollow-point style.

   This is the long-lived "Gould" 457122 or 456122 330gr (also called the .45-70-330 Express). During the era, "Express" was used to connote a high-velocity (for the time) bullet. Higher velocities were obtained through hollow pointing the bullet..

Lyman Cast Bullet Handbook, 3d Edition