I just sold my M11, Lage Upper, and Lage .22 kit.
The .22 kit in particular was problematic- I shot it three times and three times it had to go back to get the .22 barrel pressed out of the 9mm barrel because it had a dud round and ringed the barrel. This is not an upper you can take to the range and shoot all day, each Time I shot it, I out about a brick thru it before it made a kaboom and let me know the barrel was stuck. It will still shoot just fine like this, but you won't get the barrel out, my suggestion is that you just get another Lage upper and leave the .22 kit in it. I don't think it's a problem with the ammo, I think being an open bolt gun, the chamber gets dirty and the rounds start sticking in the chamber before the bolt goes home and it starts firing out of battery. This means non enough steam to get the bullets out of the barrel and you end up with a stuck bullet that the following rounds push out. One time I though I got back home without having a kaboom that told me the barrel was stuck, but it was anyway.
All of my mags cracked at the screw holes too.