Long Light Bullets (e.g., Spanish CETME and US FABRL) a dead end?

[stanc]

I want to discuss this, as well. Fascinating concept. I approach it from the angle of trying to get the best external ballistics from mass-produced, hardened steel core general-purpose bullet for something like the 65G.

My concept is a steel arrowhead like M855A1 — but with a longer tail — set into what is, basically, a solid copper "sabot."

Sounds similar to the Swiss RUAG 7.62x51 AP bullet design?

I'm not wild about the super light alloys such as aluminum because I'm skeptical of their penetration in general-purpose combat scenarios.

You're right to be skeptical.

IIRC, several years ago Frank Hackley (Frankford Arsenal's last commander) told me that the plastic-core bullet in 5.56 FABRL had very poor penetration capability vs lead-core M193.

TFB article on the 5.56 FABRL: http://www.thefirearmblog.com/blog/2014/...6mm-fabrl/