New Army "Caliber Configuration Study"

[stanc]

Some of Berger's bullets are close to 5.5 calibers long.

Yes. I figure a lead-free 130gr bullet will be close to 6 calibers long, and a companion tracer even longer. Is that feasible?

We also seem to assume that lead-free must be implemented with iron or steel. While iron and steel are about as inexpensive as one can get, and economy is one of the reasons a lot of bullets and cases are made from steel, denser "green' materials exist but are more expensive.

The Nammo lead-free bullets used by Norway have a two-piece steel core. The US M855A1 has a steel tip and copper slug. It seems logical to me to plan for using the types of materials that have actually proven acceptable to the military.