Although anecdotal in value with respect to this discussion, I will relate a single experience (one of many hog hunts I've been on) that I hope will help the OP come to terms with what feral hogs are capable of with respect to absorbing bullets placed in the chest area.
About 3 years ago my neighbor and I were hog hunting in south Texas.
He was using a Savage in 243 using Barnes 85 grain TSX bullets @ near 3200 FPS and I was using my Marling Guide Gun in 45/70 using 300 grain hollow points @ 1900 FPS.
He and I were in the process of dragging my second hog out of the brush (he had yet to drop the hammer on this hunt) when I saw a medium sized pig (150 -190 pounds) coming directly towards us at about 75 yards.
The pig was on what I refer to as the "fast walk" and when I saw him I told my neighbor to shoot him. My neighbor got nervous/wound up and was fumbling with his rifle and I told him to shoot or else I was and when he finally got sorted out the pig winded us turned and was now at a dead run from our left to right dead in front of us at about 25 yards.
When the pig was directly in front of us my neighbor shot and the pig never flinched and assuming he missed I blasted him with my guide gun.
When I dropped the hammer on the Marlin there was still no reaction at the shot and he kept on running out of sight.
Time between shots was about a second or two.
Standing there with my neighbor I was adamant that I had not missed, no way at 25 yards regardless of how fast he was running did i miss that pig, he was not so certain as he was a novice hunter/shooter.
We walked forward to the point where the hog was when we fired and found no blood.
We followed his trail/general direction of travel as best we could through the tight south Texas brush for about 300 yards, at times on our hands and knees and still no blood.
We were getting ready to come to terms with our shameful display of marksmanhip when the landowner came by in his truck to pick us up.
We went back and picked up the hog we were dragging out when this shooting went down and retold the story to the landowner.
He was convinced we had missed and dismissed it as poor shooting and said there were plenty of hogs out there and not to worry about it.
Well, while driving back to the ranch house, at a point about 3/4 of a mile from where we had shot and supposedly missed, we found him lying in the road.
Upon inspection we found that we both had hit him, bullet impacts were about 2 inches apart.
GRAPHIC PHOTOS TO FOLOW
The "Double Tap" hog is the one in the center:
Entrance wounds approximately 2 inches apart:
Entrance wounds with the hide off, note the heart and lungs show significant damage:
Entrance wounds from inside the rib cage (we believe that the forward entrance wound is the 45/70):
Exit wounds from inside the ribcage (Again we believe thatt he forward exit wound is the 45/70):
Heart lungs et al destroyed:
I didn't take pics of the exit wounds with the hide on as they were unremarkable. There was no blood loss out of the off side and the exit holes appeared to have "closed up".
Now, I do not subscribe to the point of view that wild/feral hogs are the "Terminators" they are made out to be, In my mind, bust an animals lungs and he will go down (sooner or later).
That said, this animal was able to travel nearly 3/4 of a mile with his heart and lungs deatroyed and never leaked a drop of blood (that we could find).
With that in mind, and with respect to the Op's question about the mid range 44 special loading and chest shot hogs at 100 yards, if it were me, and I was gonna shoot them with a 44 special/magnum with a cast lead 240 grain swc at 1000 fps, I would tighten the distance (considerably) and aim a little closer to the earhole vice the chest.
