Board Thread:General Nerf discussion/@comment-30049823-20200112095504/@comment-30049823-20200112101807

The Super Drum at the bottom is the one that worked, but is easier to explain because there are two colors. The channeled cylinder is orange and the drum drive axle is coaxial with it, white, and extends forward to where the square drum peg nests into it.

On the one that WORKED, the square opening of the drum drive axle would rotate through 20 positions, four of them being "orthagonal"; that is, with the square's edges being straight horizontal and vertical. The one that DIDN'T work had all the positions rotated a few degrees off, and that's why the AR is always open and the darts weren't lining up with the barrel.

So the white drum drive axle and orange channeled cylinder are held together by a sprung mesh of teeth, which will prevent the channeled cylinder from getting torn up if you forcibly rotate the drum by hand. So it seemed like that was the problem... except the mesh has 20 teeth, so snapping it into a different position didn't change the (mis)alignment of the drum's dart holes with the barrel.

BUT...

The channel-cylinder side of the toothed mesh is a separate piece that nestles into raised grooves on the inside of the channeled cylinder. So I pulled that out, rotated it into the WRONG spot (so the toothed mesh piece can now semi-freely rotate until its tabs hit the outside edge of the raised grooves that it's supposed to have been inserted into).

Fortunately, the drum ratchet tooth in the body of the blaster above the drum keeps things lined up once you take the semi-freely-rotating "slop" out of the junction between the channeled cylinder and the drum drive axle. So it actually works now.