What was also interesting is some of the bolts where one way, and some the other. I cannot remember this on any of the guides I had read.
Hard for me to understand how you would do that. I drill all my holes, clean them up, and run the bolts through from the front (top) side.
Then I turn the barrel plate over and assemble everything else in the upside-down position. I use the little bolts to stack all the layers and have everything aligned properly. The holes in the metal plate are a bit larger and will accommodate holes drilled not-perfectly-vertical.
I suppose that you could do this with some, but not all of them, but then it would be very hard to "hit" the holes exactly from the blind side. And that ridged side is where you want to be careful not to booger up the slots and tabs ("crescents" as Sandy called them).
Also, if the holes were not drilled straight, you could make the problem worse by forcing your way in from the wrong side. More, without washers, the bolt heads might almost slip through the holes.
Last, there are problems of space and fit. There is not a lot of extra clearance on either side - if the nut ends protrude too far out the bottom, you can almost hit the case at the front (spacebar) side, so using short bolts is important. On the top, you are very close to the skirt of the key when it is in the depressed position.
