Metal bats that

Hi again, Coach
Great idea doing infield/outfield practice AT ONE TIME!!
RE bats that sting. It might very well be that those 19oz. bats are simply getting through the "arc" a little more quickly and the kids are tending to "Cue the ball" out near the tip. Hit with one yourself and you can diagnose the problem more quickly.

Speaking of "cueing" brings up another thought: Pool champions use the same cue stick for thirty years...wouldn't even think of going into competition with a different one. To a lesser degree I feel the same way about bats.
My son got a TPX as a thirteen year old that was too big for him, (grandfather had read an article). I wrapped about seven or eight turns of athletic tape around the handle three inches up, and then moved it down one inch each year till he was on the knob. By the time he went off to college with it, it had a decided oval shape, and was the very devil to get a new plastic tip into the barrel.
(Manufacturers do have those by the way)
It finally fatigued enough to crack and he went shopping....Finally bought an old used TPX identical to the one he had worn out. Loves it.
Best regards
Bean