yes Ulysses, the worst thing is that this majestic fish will now become part of the underwater food chain.
The shot was "ok" at best, center of mass, but below spine, just above stomach. I do adjust and do the test you talk of, I saw that in the Spanish "apnea" magazine and even teach the trick to my buddies. Your attached documents are very good.
I lost a little traction. I was on my own (not good) and very aware of hyperventilation (adrenalin). It was 12M exactly, well within my range.
But with the huge explosion in the cave, the floppers "stuck open" position is not going to last, and it was probably closing, and sans firing jolt, not properly opening again.
I am not using less than 70mm floppers again. These look cool:
Squalo shafts for arbalete gun by Salvi & Figli S.r.l.
(I looked for the hurt fish and found a 4Kg grouper on the way, now in the freezer. Funny how small it looked after the one I lost..)