05-17-2011, 03:29 PM
stanc Wrote:...An M855A1-type 6mm bullet (with 5:1 L/D) would likely weigh less than 90 grains, and have a BC subtantially lower than the 95gr lead-core VLD on which I had based the 6mm Optimum's estimated performance.I get 80 grains when scaling a 62 grain bullet from .224" to .244"
stanc Wrote:I might be mistaken, but it appears that eco-friendly 6mm bullets of 100-115 grains may not be feasible. The Barnes banded solid in this caliber is only 75 grains, with a 4.4:1 L/D and an unspectacular 0.341 BC...Don't give up too soon!
JBM shows the 80 gr TTSX as having a length of 1.083 inches. I surmise that part of the reason for keeping the weight down is stabilization in the standard twists for 6mm rifles. Density and length both play a role in determining twist needed.
The Berger 115 gr VLD bullet has a bullet of length = 1.365 inches. We can get to about 100 gr by stretching the scaled M855 to this length.
We will need to check in more detail, but I'm pretty sure that a 100gr class "green" bullet could be made to work in a rifle with appropriate twist.
Remember the cardinal rule in system optimization: The optimum is always defined by the smallest thing that will work... It's frustrating for those of who are in the overkill crowd. About the only exceptions to this rule arise when packing factors allow the same number of items to be stored for the same cost as the slightly smaller one. (There is always the fiat applied by someone with sufficient authority.)