The countless 223's I made for my Sport were only 2700fps. Considering I was shooting for 3100, pretty embarassing.
My Chrony pointed this same thing out to me, but with LC military surplus ammo! Shooting the LC stuff through a 16" barrel didn't even come close to the magic 3200 fps that is held out to be the standard velocity of the M4 rifle. I giggle when when I see it printed now!
I did get the LC ammo to come close through my 22" DPMS varmint barrel, though!