When we did it, years ago, when we could fast draw in someone's garage, within city limits, we opened the flash hole up about double, to let more primer pressure through, it also lessened the primer back-out that can make a revolver harder to cock. But DON'T EVER use those cases for real reloads after that modification. CCI used to sell plastic bullets and cartridges, and I had a set called "Red Jet" which had aluminum cases with a large flash hole, and they also sold the wax bullets. This is like 40 years ago..