Step 1: Barrel.
Step 2: Grenade launcher.
Step 3: The main body
1: The whole trigger assembly and handle.
2: More of the trigger.
3: Even more of the trigger. Why did I take so many pictures?
4: The inner barrel.
5: More of the inner barrel and the ram.
6: The GL sear.
7: The GL sear again. Note that the sear is exactly the same on both sides.
8: I don't know what this is for, but it is there any way.
9: The carrying handle.
10: This is the back of the main body.
11: The GL trigger.
12: The GL trigger again.
13: Piece one.
14: Piece two.
15: Piece three.
16: Attach piece three to the main body.
17: Now piece two.
18: Then add piece one. Ironic, ain't it?
19: Put the GL on the front section.
20: Attach front section.
21: Attach carrying handle.