The FBI made a simulation of Oswald's supposed bag. But, all they did was fold some paper and tape it. They didn't really make a bag. They didn't create the flat bottom and crisp sides that we see on Montgomery's bag.
And then when CBS tried, they did about the same thing: just wrapped the paper around the rifle. They didn't make a bag.
Notice that the CBS bag is cinched up on both ends. They are practically indistinguishable. They certainly did not duplicate Montgomery's bag with the sturdy flat bottom. All CBS did was wrap the rifle in the brown paper- just like wrapping a Christmas present. They just wrapped the paper around the objects. But, Oswald's bag had a flat bottom; it had distinct sides with crisp angles. It looks like a real bag, which these two simulations by two rather large institutions, the FBI and CBS News couldn't do.
So, how the hell did Oswald do it?
This bag is a smoking gun. Oswald could not possibly have made it. You've heard of the magic bullet? Well, this is the magic bag.