[Oldeyes]

The folks that develop sub-sonic rifle rounds often recommend boring out the flash holes to increase the effectiveness of primer ignition of the slower burning and typically lower pressure powders. They also recommend keeping the over bored flash hole case segregated to avoid potentially quite dangerous over pressure situations resulting from using those cases with standard faster powders and load data. Thus, in your case I would tend to err on the side of caution and not use the over bored flash hole cases in my normal reloading routine.