Very nice! I have one of their Mk18 SBRs and like it a lot. For even quieter shooting with subs you may want to look into the JP Enterprises silent capture spring system, it eliminates the spring noise in the buffer tube.

I should get my stamp back any day now on my lower that I had converted, it's going to be the home for my 8.5" 300BO upper. I've got the option to run my Silencerco Omega9k on it for maximum compactness or my 30cal can for max sound suppression. One of my holiday chores is to load up a batch of 1000 cases, half will be supers using the Hornady 125gr SST and the other half will be subs using the 220gr Sierra ProHunter.

Edit: Forgot to add. I'm running an MRO on my Mk18, nice sight. Be sure to get the new Trijicon cover for it.