Optimized Caliber

[Variable]

I still don't see a huge need for anything other than a 5.56 in a PDW though, unless you go below a 10.25" barrel length, which is an extremely small niche market anyway. 10", 11.5", and 12.5" 5.56 carbines generate plenty of velocity, despite what all the claims have been.

I don't keep up with the 5.56 much anymore since we just use whatever we're given at work, but what is the best general purpose "serious" ammo these days? I still have Mk262 Mod 1 for my personal 6933, but we don't get issued it and I don't have much left.