If you notice when you manually open the lever slowly, there is pressure against the lever that will make it jump that first bit. If you place a round in the magazine and then pop the lever that first bit, you will see the round move back into the reciever slightly.
Although some claim it isnt true, there is pressure from the magazine tube spring being placed against the lever in that last section of closing if there is a round in the magazine. If you gently press against the lever when closing that final bit and look through the small hole at the front of the loading gate, you will see that you can move that next round back and forth, but that there is no movement of the bolt out of lockup.
In addition, just before complete lockup, the lever engages the trigger safety which is spring loaded. I have heard of this being modified to have less spring pressure.
So there are 2 springs placing pressure against the lever, if there is a round in the magazine, at that very last portion of its closing cycle. Those 2 springs also have the assitance of gravity on the lever.
One thing I noticed is that as I became accustomed to the rifle and started operating it quickly after each shot, my grip had relaxed and allowed my fingers to be bumped in the lever, since I was no longer wrapping my thumb around the tang.
