I have always been of that assumption, namely since 16" .308 rifles have become "in vogue". You know, the SOCOM M1A, shorty FAL's, Saiga carbines, etc. I have always felt that 18" is about as low as you want to go with a .308 and still retain decent ballistic performance. My over-simplified assumption was that a 16" tube basically turned the .308 into a "heavy" 7.62x39. But is this true? A standard, mil-spec 147-150gr FMJ does what, ~2750fps from a full-sized M14/M1A? What would a similar round do out of a 16" barrel? Is there still enough "oomph", if you will, to make it a better (and in most cases a more expensive) choice than 7.63x39? I'm not talking about 800 meter kills here, say out to 300 meters. What say GlockTalk?