Thanks Matt. I've got a cut down M-11/9 upper that was used for some of the initial testing on the new W bolt before transitioning to the OEM M-11A1 bolt with a 9mm barrel. Much to my surprise, I didn't experience a single piece of 9mm brass being caught in the smaller port. Still, it seems use to enlarge the original port size just slightly if it doesn't result in an unsightly bolt gap. I'm interested in seeing the bolt gap in the opened up ejection port on the original M-11A1 upper with an OEM size bolt.
Now, to prevent this thread from being derailed, I'll share my .22LR experience.
I've seen, handled, and shot Kermit, Tod's .22 drum fed creation. It's somewhat crude construction didn't prevent it from excellent functioning. The concept is sound.
While waiting for Craig Wheatley's AM–15 upper to be produced, I purchased a Bazooka Brothers adapter. Despite my best effort's I could never get it to shoot more than 15 to 20 rounds before it stuffed up. Even a trip back to the manufacturer for an upgraded defend tower didn't the problem. They blamed it on my 22 conversion which was total bunk. The last time I took the adapter out I got frustrated very quickly and switched to 30 round magazines. After running 14 street bags without a single malfunction I sold the Bazooka Brothers adapter and never looked back.
Shortly after that, the AM-15 uppers began shipping. At least four of us here in town received them at about the same time and we all had problems. One owners pinned his feed block in the same way that Val pins feed blocks on the American 180. This seemed to provide better results. One of the owners returned his for service several times and they eventually refunded his money. Like the Bazooka Brother adapter, I sold my AM-15 upper, drums, wonders, etc. and I have no regrets.
For the life of me, I don't know why I never purchased a Lake Side .22 belt fed upper. Well actually I do. Two of my friends here in town purchased them for thir M-16s and they didn't run anything like the 1,000 round dump video that was posted in this thread.
At some point I asked one of my buddies to kick me square in the nuts if I ever so much as considered buying another .22 conversion. He didn't find out about me buying a Lage M-11/.22 conversion which is probably my favorite conversion of all time. Having said that, I had a .22 conversion for my Vector Uzi that ran ver well from day one, and after considerable tinkering, My Ciener style. 22 conversion for the M-16 ran extremely well with 30 round stick mags but it was very very fast.
Today, I'm down to the Lage .22 conversion and I hope I'm done. If I need another .22, I'll buy one that's built for that caliber from the ground up.