I hear stories like the OP….and just scratch my head.
Im blowing through animals with my 47# recurve, 553g 340 spine carbon arrow and 2 blade heads. I couldnt tell you my FOC. Not just a couple animals …everything. Heck I shot an 800# moose a couple months ago, first shot 30-ish yds….complete pass thru with the fletch hung up on the off side broken rib with the arrow sticking straight out.
The moose does a couple 360’s right there trying to get its nose on the tip of the arrow. It goes down. I run in as its right before dark, the animal struggles to its feet and I bury one 24” in front of the shoulder quartering to me. As the animal gets to its feet then turns broadside, I put another arrow right in the chest complete pass thru on the ground 20’ past. The moose staggers 2 steps and rolls down into a creek DOA.
I bareshaft tune. I do have a long DL, 31” so I gain energy there but I bet my setup doesnt make 40KE.
I think a guy can take all of this FOC, KE and Momentum stuff the influencers preach and throw it in the trash. ( I will keep it respectful and not tell you what I really think)
Perfect arrow flight with a decent weight arrow and a tapered 2 blade head is a very effective arrow, IME.
Of the 12 animals I’ve shot in the last 2 years with this whimpy setup, moose, hogs, deer and Javelina, I only had a couple in the off side shoulder that didnt pass thru. Ive got 40 years of bowhunting to draw on, seen hundreds of animals die to an arrow- inc some big critters, apx 60 elk, water buff, etc.
OP, something is not right, here are the reasons for poor penetration;
Poor arrow flight ( numero uno)
underspined arrow
Inefficient BH ( like a mech or short chisel point head)
BH curling/ breaking/ bending blades
Low energy
Hitting heavy bone
Heck, I shot a couple of med size hogs last summer with my 40#, 375g setup I use for 3d, just to see…..you guessed it pass thrus. ( So this doesnt get misinterpreted, I wouldnt hunt with that setup all the time, Im in the process of tuning a new hunt bow 52-55# limbs and a heavier spined Axis 300)
Bottom line, a perfect arrow with a 2 blade is an amazing killer….