The way you describe looks structurally impossible based on that image. I can kind of imagine what you're thinking, and I don't think it's possible with the way you drew it.

The key to drawing transforming weapons is to draw tell-tale signs of how the weapon transforms, your weapon is drawn thick, curved, and thus inflexible so it is impossible to visualize the way you described based on that image. For instance, Ruby's scythe is largely folding, so there are a lot of bolts and screws on many of the parts, mostly around the blade where it folds out into the scythe blade, while the shaft and sniper barrel appears to be a slide-out type.

Of course they don't have to be easy to explain or even possible, so long as it is easy to visualize, like Coco's minigun/bag.

Being able to visualize it is the most important part, not just easy for you to visualize, but for others too. Because we can't exactly animate these things.