[ScottRiqui]

It appears that you have a non-M4 upper (no ramps cut into the receiver) and a non-M4 barrel (the ramps in the barrel extension come just barely out to the edge of the barrel extension, but the circumference of the extension is still an unbroken circle.) As such, the combination should work together, but if you're having feeding problems, you could cut shallow ramps in the receiver to "blend" the transition from receiver to barrel extension.