This is now resolved thanks to searching the forums and one of variables posts from way back. Should this be a sticky perhaps? Not sure how common this problem is. Maybe not since I just found one instance of it.

Anyways ever since I got my XCR it wouldn't want to lock back without a magazine in it. Then after a day at the range I took apart and cleaned it and it was actually releasing the bolt when I hit the mag release. Anyways fixed now, kudos for the help on the forum, just thought I would share.

Quote Originally Posted by variablebinary View Post
Check the bold hold open.

It's two pieces. It's a pin that is cross stacked with another pin, but not threaded. So what can happen is the stacked pin gets pushed back for some reason and its set too far rearward to catch the back edge of the magazine follower. When the mag is empty the BHO stays down, and the bolt doesnt stay open

Tap the stacked pin forward again and be sure it comes into contact with the rear of the mag follower.

Robinson should make the BHO out of one piece, or use threading so it doesnt get pushed to the rear