Ditto. The manual clearly doesn't depict the tactical. However, I guessed at the assembly, and then after parsing the images enough, I think that's how it goes together. Also, if you're having trouble with the spring shaking around, try placing the spring inside the red cap (don't know what it's called, but it's the cap that goes farthest inside, where the mags will touch it) before you insert it in the tube. Everything works now for me.
I'm accustomed to over-unders, so the tactical mecahnics are new to me.