Given a buffalo's exceptional senses, it is not easy to get in a killing shot at a buffalo before it becomes aware of your presence. And when it does so, it will invariably turn to look at you with its nose uplifted. Because of this, it is my experience that the majority of shots at buffalo are from the frontal angles. A buffalo's frontal chest skin is almost an inch thick, loose and supple. This is its frontal chest armour, used when it crashes head first through thick bush with is head held high. His thick supple skin absorbs and dissipates energy - in the PH'ing world we call it the trampoline effect and it can seriously affect a bullet's terminal performance when the bullet is too light and too fast. What works best for overcoming the 'trampoline effect' is heavy for caliber, relatively low velocity bullets with lots of momentum.
I learned this lesson when still a learner Zim PH back in the early 1990's. Our client was very proud of his 'hot' .375 H&H reloads shooting 300 grn Nosler partitions at a measured 2600 fps. We ambushed a large herd of buffalo as they grazed slowly towards us. In the front was a nice herd bull which stopped 50 paces in front of us with head uplifted when my tutor PH tapped the magazine floorplace of his bolt actioned rifle with his gold wedding ring. The bull was directly front-on to our client who shot him sqyarely in the middle of his chest with the 300 grn Nosler Partition. I was directly behind our client, watching the bull through my binocular and I saw the puff of dust where the Partition inpacked - shot placement looked perfect. The bull dropped to the shot as it lightning struck but was instantly back on his feet and quickly lost in the dust and confusion of the milling and then stampeding herd before any backup shots could be fired. To cut a long story short, we never found that bull despite looking for it for the next three days and in the end concluded the shot was not fatele because it never entered the chest cavity. For me, this was a real learning curve and now more than 3 decades later and a three figure buffalo tally, this was the only buffalo I ever saw shot and lost.
At the time I owned a 9,3 x 62 mm, purchsed from an oldtimer who had been for his long bush career, the crop protection officer for Triangle Sugar Estates - where during the course of his duties he estimated he had shot 'at least' 600 buffalo with this rifle. He loved the 'Nine-Three' as he called it and said it was a lot more effective on buffalo than the .375 H&H. In those long ago days, the recomendation was 'only solids for buffalo' and he prefered the Nine Three because of its lower muzzle velocity with 286 grainers worked better on frontal shots and from side-on such bullets usually did not exit as a 300 grain .375 solid usually will.
As soon as I aqcuired this rifle I got Ken Stewart to make me about 500, of his bonded 300 grain .366 expanding Hi-Performers with a flat nose and a 2 mm steel jacket. (these bullets were very similar to Woodleigh Weldcores) At an honest 2300 fps they were wonderfully effective on buffalo, even with frontal chest shots, and when I finally sold this wonderful rifle it had in excess of 650 buffalo 'scalps' to its credit.
I tested many different bullet types in the .375 on buffalo and without a doubt, the most effect by far was the 380 grn Rhino. So large were the permanent wound channels these bullets created that I used to recover these bullets by just sticking my gorilla-length arm into the wound channel and pull the bullet out! The only problem with these bullets was their quality - every batch was different so I eventually gave up on them.
North Forks 350 grn SS and CNS are the next best and most effective .375 buffalo bullets at velocies in the region of 2350 fps and they work extremely well with placed perfectly. The 350 grn CNS will exit from side-on while a SS will not. On a direct frontal shot, the thorasic inlet is only the size of your hand - miss this opening into the chest cavity and it is possibe for the overlapping ribs to deflect the bullet. My experience is that this is less likely to happen when heavy for caliber bullets at a lower velocity are used.