Twice I have run destroyers out at numbers between 100 and 120. Once, which seemed to take forever, I didn't count but would estimate 150. Of course the tendency would be to overestimate the number. Last time I ran a destroyer out of depth charges was the 115 guy and I never left periscope depth for the whole time period. Spent much of the time taking photos through the periscope trying to catch a depth charge rolling off the rack. Never did get a good shot and I'll have to try again.
I'm on October of 1943, so I imagine the destroyers will be getting better and the strategy might need scrapping, but I sure would like to get a shot of a depth charge rolling off the rack from a destroyer out to kill me. I understand Mush Morton actually did that. Hold it. Mush Morton died...
Interestingly, after a destroyer runs out of depth charges he continues to make runs as if he still were dropping them. So he can keep you pinned if you've gone deep and call in his nice DD buddies, whose racks are full. If you're at periscope depth you can set him up for a nice shot up the poop chute at the end of one of his dry runs (a booster shot as it were)
. Then you're gone!