Just a thought:
1. One batch of all the same brass, 50 pieces. 25 with factory flash hole, 25 with enlarged flash holes.
2. Same powder charge, same bullet, same primer in both sets of 25 pieces.
3. Do random rows of five rounds in your ammo box - one row of five rounds is factory flash hole, another row is enlarged flash hole, and so on. BUT, have a third party load the box and not tell you the pattern.
4. Go shoot ten groups with the loaded ammo box, see if you can tell a noticable difference in group size then.
