Because of the high density, relatively short lead or lead-alloy bullets offer excellent ballistic efficiency.
Such bullets are inexpensive but equally limited in accuracy, terminal performance and ballistic efficiency.
While ballistic efficiency
is hard to dismiss as irrelevant, it's also hard to love.
Overall, bonded designs provide a significant performance advantage over conventional non-bonded lead-core bullets and are available in a wide variety of styles from exposed-lead nose to polymer tipped designs for improved long-range ballistic efficiency
The short powder column and sharp 35-degree shoulder angle contribute to the WSM's ballistic efficiency
5mm bullet, while case length was shortened slightly to 42mm, just enough to accept projectiles of higher ballistic efficiency than the original length would allow.
8mm SPC is quite adequate for engagements of point targets to a distance of about 500 meters, but for shots at longer range, greater ballistic efficiency is called for.
They placed their emphasis on: A) superior accuracy, B) downrange ballistic efficiency
for retained energy and a flat trajectory, C) positive controlled expansion on target, and D) a lasting finish that retains a fresh visual appearance even after long storage.
To achieve a flat trajectory, and thereby improve long range capability, requires a higher degree of ballistic efficiency than can be provided by the 6x45mm.
5mm and 6mm, allowing it to be loaded with projectiles of higher ballistic efficiency, and these smaller-caliber versions would undoubtedly be better general purpose rounds.
This significantly increases ballistic efficiency without reducing accuracy potential.
Third, it allows the manufacturer to include an unusually tiny meplat, again improving ballistic efficiency.