Recommendation for a 300 Blackout Complete Upper

I have an existing M4 style carbine that I would like to also use in 300 blackout.



I was thinking this:



http://ift.tt/1Dt4ekf



Or something a little nicer:



http://ift.tt/1Dt4boD



This is the current rifle, which was purchased pre-ban:

Attached Images

DSC_0004.jpg (95.0 KB)

Recommendation for a 300 Blackout Complete Upper