The 55 grainer does have a hard time getting through the rib cage. Sometimes it doesn't even make it to the rib cage. I shot a buck at about 100 yds. one year at an extreme upward angle and the bullet hit the upper bicep on the right leg. I was angling for a heart shot just behind where I hit. The deer took off like a shot (pun intended) and I thought I missed it completely. I shot it on a dead run (another intended pun) and it went down like a pole-axed steer. When I checked the front leg, the muscle had been pulverized but not a single piece of the bullet made it through to the chest...none at all. I changed to some 70 gr. bullets my friend, a commercial reloader, had and never had any trouble dropping a deer again, no matter where I hit them or from how far. I also used that same load for varmints, not wanting to change the zero on my AR-15 and had great luck with it. One day, an interloper from the next farm over the ridge, drove up on his 4-wheeler while I was hunting groundhogs. He saw my "black rifle" and snickered out loud. After a few derisive comments about using "that thing" to hunt groundhogs, one stood up with its back to us about 150 yards away. He said to "try to hit it," so I eviscerated it on the first shot. He never said another word, started his 4-wheeler and went back over the hill.
“The ultimate aim of martial arts is not having to use them”
― Miyamoto Musashi
"The only gunfight won is the one avoided."
― The Rukh
"Ignorance is treatable - stupidity is terminal."
― The Rukh