I just picked up a BRNO model 304 12 ga v 7 x57R combo gun. I have owned many BRNO doubles, but never one in this model. It came taken down. How does one put the bbls back into the receiver????? I cant even tell if the forearm comes off! -- there is no latch on the forearm and it does not appear to want to slide forward off the bbls.

I can just about lever the bbls on, but the extractor cam on the left side catches onto the top of the receiver frame --- help!