Here in Ottawa (where the current style of pyro grenades where invented as far as I know) we have been making them the exact same for years. The only problems I have ever heard of grenades being packed extra tight, using larger charges, or throwing them at peoples heads on purpose are all problems only run into at Quebec games. In Ottawa we have, as said, been making them the same for years with the same charges (airbombs) and have never had a problem outdoors.
Notice how I say Ottawa and not Ontario, there are some teams down in the Toronto area who have a similar arms race to make louder and more powerful grenades. I only run into those people at really large games like at Rawdon and the few games I go to in Southern Ontario usually don't allow grenades. Ottawa players safely used grenades even indoors at the mill for more than a year before some Quebec ass holes (no idea who they where but I have never seen them again, all I know is they had Quebec plates on their vehicles) started to double and triple wrap grenades in duct tape to make them louder, threw them directly at people without calling anything, and in one case lowered one on a string from one floor to another directly beside someones head (a team mate knocked him out of the way so he didn't blow his ear drum.)