Okay, looking for a sanity check here, as I may have come up with an option that's a little less money but I'm not sure if it's cost effective.

AU has the 6951 for $1021 out the door, and after the transfer fees, I'm probably looking at $1061 + the cost for mags. Let's just call the total $1100 with 3 mags on hand.

I've found a 9mm CMMG radial delayed blowback barrel/BCG combo and a BCM upper receiver for $640 out the door. Add in two mag converters and I'm looking at $700. I have all of the other parts on hand to make it a complete upper. This then also allows me to run the upper on an existing AR-15 lower (which I have plenty) as well as giving me the option of cutting the barrel down, should I want to, and put it on a SBR AR lower (which it will probably already be sitting on).

The local large gun store didn't have any 6951s in stock, which would have simplified this process.

So $1100 vs $700 plus some gun-smithing (which the 6951 would need anyway). No extra pain in dealing with the transfer. Is the $400 savings worth it? Am I missing anything else?