This is not the update I wanted to give but it is what it is. I have spent way to much time trying to get this upper receiver running well and I think its time to move on. I think using the mag well for the ejection port was a bad idea, it just seems to allow to many opportunities for spent rounds to bounce around and not make it out of the receiver. It also makes it hell trying to figure out feeding issues since the top of the chamber is blocked by the drum and the long mag well makes it impossible to see anything from the bottom. So on to version 2 with a right side ejection port. This design should make the transition to the baby mac possible as there was no way the mag well ejection port would have worked with the short receiver. I've got the 3d models done and I've started 3d printing some of the parts for fitment but now that warmer weather is here my spare time is going to be limited so its going to be awhile before I'll have the prototype built and be able to start testing it. Version 1 and version 2 below.