Did you get this sorted out yet? If not, try Build It Yourself Forum
at gunsnet.net. In the hey-day of the AK home builds from kits they were the encyclopedia. To that end, have you tried the 'search' feature of that, this or any other forums? There's a plethora of info therein just waiting to be tapped.
EDIT: You might try searching 'failure to chamber'. It's more specific.