Is the locking mechanism on the new manufacture AO drums designed for the semi-auto magazine catch only? Will they lock properly with a standard GI magazine catch? Does AO still use their semi-auto offset magazine catch? My last AO semi purchase was in 2002. I am not sure if they changed. I am looking at getting a new AO M1927 SBR and wanted to send it off to PK for the bolt lock/selector switch modification as well as the GI magazine catch so it will work with standard GI magazines. He did amazing work on my AO semi M1. Off the topic of drums, but does anyone know where to get a good Cutts Compensator blank fire adapter? Thanks, TC