I used a 6x47mm one year, after neck surgery. It had a 27" barrel, and I loaded the Barnes 85XBT to 2900fps ( just like a 243) It was a popgun in recoil, and a real killer on game. Now, I shot exactly 3 animals with it. A nice in velvet Axis buck,125yds, quartering away. I walked up to him and gave him another as he was not quite expired. I then shot a huge Scimitar Horned Oryx, through & through the base of the neck, DRT at 184 lasered yds. I gave him an insurance shot at 75, bullet went through heart, broke his spine, stopped under the hide. +20" penetration and bullet weighed 83gr. I then shot a Jackrabbit that afternoon, bullets zipped right through, thought I'd missed, he finally plopped over/kicked his last. Extreme sizes, but interesting results. I had it rechambered/bolt face opened up to 243 and gave the rifle to a friend in South Africa. He used Winchester 100gr PP factory ammo. He head shot Impala with it for culling,etc. I've seen some strange things with animals. shot with all kinds of calibers, it seems to have no rhyme or reason to it, ha.
The hunt before the one above I did with a 220 Swift and the then factory Federal load of the 55gr Trophy Bonded bullet. Shot an average size muledeer in Utah, then went down to Texas and shot an Axis doe, and two really nice Blackbuck antelope. On it, they all dropped, but then tried to recover. I had to shoot the muledeer, axis doe and the Blackbucks again. Seemed to me the 'shock" on their body size affected their nervous system, but it sure didn't kill them on the first shot.
The axis doe (80yds) was double lunged, the muledeer was center chest (also around 80yds,right over the heart) the wind blew the first shot on the first BB,(135yds) hit him in the ham! He took off ( these are tough/high dollar animals!) I swung ahead and "rabbit shot him", accidently hit him in the neck! ( I didn't tell the guide it was an accident,ha) 2nd BB was high shoulder shot at 125yds. He dropped, recovered and was trying to get up, neck shot him at 75yds as I approached. Recovered only a couple bullets, all .45 caliber and weighed 55gr! I sold that rifle to the guide ( he really wanted it) and I went to the above 6x47mm, but chose the Barnes XBT.
I later used a .224 TTH ( 22/6mm) with the 75gr Swift Scirocco around 3750 and shot a 275# hog at 25 yds, neck shot/close to the head, bullet stayed inside/fragmented, but the hog was drt. No follow up needed. I just recently had that rifle rebarreled to 7mm08, which I had used a few years back with 139SST Light Magnum ammo to heart shoot an exotic sheep around 200yds, he ran downhill for about 50yds, piled up. I also shot a 100# deer in Georgia one year at 15yds, 7Remmag/150 Nosler Partiton and he ran 60 or so yds, lungs jellied. I also used a 300 winmag on Texas Hill country deer with Federal factory 150 (sierra pro Hunters) and they "syphoned pices of the lungs/tissue out the exit hole at 45 yds! They were hanging out, and the deer ran 10 yds or so. I shot one buck, head/neck juncture, he dropped of course. I grazed the head on a big doe around 90 yds, she flopped around until I could get a second shot on her head. (gruesome!) They do what do, like I said, 'to me", I see no rhyme or reason to what they do, ha.