The first ones I made were a laminated block and were downright ugly. The second iteration was the slightly angled "T" with a flat front, but it still looked too blocky. I had to add the little tabs on the 9 and 45 to prevent the next bullets from daisy-chaining all out at once. The .223 is the final iteration, with the tube moved back enough so it didn't require the tab. The fronts were then angled to allow more room for my fat fingers (the ones that aren't grabbing the bullet).
It's hard to tell from the pics but the tube has about a quarter of it's diameter still attached at the back of the bullet opening to support the bullet, and it is held off the back of the slot to allow easier grasping of the bullet. The angle of the tube/face is just enough to keep the bullets in place at the bottom of the tube. There is enough friction in the hole for the tube that it can be adjusted up or down for varying bullet lengths.
And yes, there were several cocktails involved in the design process (but never while testing!).
