So with the cloud 9 quakeblast has a known issue when turning it into gun mode and its one with both the normal and even more so, the clear version.
You need to unscrew the handle and manual move hinge, first with cloth and pliers and then with fingers, to loosen it so you dont risk breaking it off the handles.
Got a video showing it and also will link a vid to another vid on YouTube that shows you how to not break the arm cannon peice off. ( currently having trouble in refinding the vid, but we could just make another vid to show how) but to put it into prompt, get the arms to the point before putting the muzzle on, split the arms apart slighly (have the inner sides together at the top still) then put the muzzle on and click arms back together and it now holds inplace without needing any force.
https://youtu.be/BijPRxnMBxk 