broadheads
It's been maintained by others as well as myself, that a "cut on contact" head penetrates easier (read 2 blade like the old Bear Razorhead or a Zwicky, or 3 blade like the Woodsman or the old MA3) than any conoidal or truncated point. A loose test of this can be done by pushing a broadhead by hand through a taunt sheet of fabric/hide/cloth. But......
Lots of deer have been killed/passed through, with a 3 blade Muzzy and 55lbs of draw weight. My first thought is that you picked up either one or both shoulder blades. Or perhaps the arrow glanced off the spine? Did you quarter and butcher that critter yourself? If you shot through one or both shoulder blades, you have plenty of bow/arrow and I would not worry about it. My light bow is 55 lbs with a 400 gr arrow, and I expect pass throughs on the chest/ lungs, unless I hit major bone.
My second thought is that your bow is way out of tune, and the arrow arrived with significant yaw/fishtail, , or that you hit a limb with same effect. The arrow arriving skewed could really effect penetration. If you/ve not done so, I'd shoot a few paper tune shots with your broadhead combo to assure true arrow flight.
Personally, I'd avoid mechanicals like the plague. If "something" has to happen before the point can cut, than the likelihood of "something" not happening is also present. Remember our old pal Murphy? Arrowheads have been "cut on contact" (fixed) since ancient history, maybe as much as 50,000 yrs, depending on what you believe. If it ain't broke.......!!!!
Finally, I'd avoid dorking with my bow and set up 'till AFTER the season, provided all seems in order at the present time. One season, I had an injury, and had to reduce my draw weight accordingly. To keep my velocity up, I reduced the weight of my shafts/head combo as well. I thought my new arrangement was ready, but I then proceeded to miss a bunch of deer.
Turns out the new set up would not consistently group broadheads/poor arrow flight. When I was fully healed, the late season was still running. I went back to my old arrangement, and killed the next 3 deer I shot at.