I tried to add a stock to my Lego gun but I was not able to convince myself that the stock-independent grip is good enough for simply attaching a stock. There was simply no place where it made sense to add something stable. So what I did today except designs and concepts was to completely redo the grip and it's thumbhole. Trust me, it was hard to find a final shape. I'm glad I was, at last, able to remember the way thumbhole stocks look like and what fine details are necessary. I underestimated how important it is to provide a 1 stud wide area beside the other 3 studs wide ones. I'd get blister from it otherwise! Whatever. I also added dark grey parts to make the grip look and feel more like a single piece of Lego (which didn't really work due to several reasons). I also made a nice litte charger grip that works very well for charging individually and both at the same time.
Well... Only thing left is the chamber opener. That one may take some time. Oh and the stock of course. I'm still hesitating because I don't think that a stock is really necessary. Independent from that fact, my "Faulenzerkralle" mechanic is simply useless as it seems. I simply don't know what sense it makes to create it because the way of locking it to position is as better on it's own to be a stock. I'll make a straight rectangular block expandable by up to 40 percent or so. Should be enough since a normal grip is already present.