Well, I don't know if anyone has heard, but Calico is coming out with a .22 upper for the MAC. Takes their 100 round mags.
I have read a lot of crap about the Shrike issue, but I went ahead and put down my deposit.
Their turn around time is supposed to be about 90 days, so I will post my experience when I get it if anyone is interested.
I have been waiting for the Lage .22 upper, but he is building it for the M11 first, which puts me way down the list, so I went for the Calico.
I have a pic of the prototype but there isn't any video of it running that I have seen.
I also had one of the Flemming uppers....you all have heard that story as well.
I am not affiliated with them in any way except that they have my money for a .22 and 9mm upper for my MAC 10/45.
Wish me luck.