You know it. I have done this a few times then sat there like a dumbie for 3 hours messin with it before going ohhhhhhhh yah forgot, click wow it slides right in.Did you "uncock" the bolt when you had it out? It needs to be cocked to re-install it.
Can you take pictures of the parts you have? If you have something close to mine. I could probley walk you threw putting it together. The problem with the exploded views is that it has all the different parts for all the different models.