F Spike's Tactical 16" 5.56 M4 Carbine Length AR-15 Barrel $211.50 SB51605-M4 show more like this Calculated in Cart Primary Arms F Spikes SB51605-M4 $287.96 SB51605-M4 show more like this Butt N' Barrel F Spikes Tactical Barrel ST-16" M4 Carbine LE-5.56 $319.95 SB51605-M4 show more like this Right To Bear