For the 6.5 PRC, here would be my personal criteria, based on your 400 yard no go line.
We have 3 problems with the scenario to get through.
1. What animals are the target? What it the terrain?
2. What is going to be your Impact Velocity under 100 yards, and your Impact Velocity 100-400 yards.
3. What is your desired outcome? Bullet exits, and lower probability of bang-flop? Or Bang flop and bullet doesn't exit?
Question 1.
All four of those bullets can survive a high impact velocity sub-100 yards, in any animal that walks
I never had a Scirocco that would shoot as well as the Accubonds. Even though Swift A-Frame is very popular on larger game in Africa, I don't see the necessity to use that kind of a bullet and I don't prefer an exit wound normally. We are talking normal plains game Zebra to DIKDIK range.
I have never killed an eland or a giraffe, but I think they are different. Killed hundreds of animals, with a lot of different bullets. Mostly out of Africa, but I have killed 24 African plains game animals as well.
So what are you wanting to kill, and where?
Question 2.
Every bullet has a designed impact velocity from the manufacture that they test at lots of distances. You want to be in that impact range of velocities with your bullet.
People talk about bullet failure all the time, but what they rarely consider is that it is not normally the bullets fault, it is normally operating at a less than optimal velocity when it impacts and has a "failure". Bullets have a design range, and keeping it in the design range is optimal.
You can call Nosler, Hornady, Barnes, Swift or anyone else and ask what the bullet impact velocity required for optimal work would be. Sometimes it is published, but not always.
Question 3.
I am a bang flop kind of guy. I like massive wound channels caused by Cup and Core bullets. You can achieve similar results with deformation (bonded or mono-metal bullets) at high speed.
Your four bullets the Accubond, Partition, Scirocco and A-Frame are not generally known for massive wound channels, but for either exit wounds or full penetration. High speed (sub-250 yards for the Accubond or Scirocco, and sub 140 yards (approximately) for the Partition and A-Frame will achieve a bigger wound channel.
Mon-Metal bullets like the CX and Barnes X series bullets among others must be driven at blistering. speed to achieve the same wound channel. They suffer at distances as they don't have the mass to continue through muscle, guts and bone. I have reasonably good experiences with the Barnes X at 350 yards at a 3300 Muzzle Velocity in a 300 Winchester in the 150 grain bullet. It is moving very well, but it is not as dramatic as a cup and core bullet at the same distance. That the cup and core bullet weighed 190 grains (Berger) shot placement was the same, animal was the same.
Last year I had typical Barnes X performance on 5 animals (bullet was an RWS HIT which is very similar) red stag, red hind, red spike, wild boar, fallow deer buck. All of them ran 40-100 meters. All of them in the lungs, one in the heart. Impact distance was 40 meters for the red spike, 80 meters for the stag, 100 meters for the hind, 200 meters for the fallow, and 60 meters for the boar. This was a 200 grain mono-metal bullet with a plastic tip, similar construction to the Barnes X or CX. In a 10,3x68 RWS (.413 bullet on a case that is mid-length between a 338 Winchester and a 416 Remington). So moving very fast! Every bullet exited, every animal ran minimum 40 meters, some ran 100 meters.
The year before I had the same exact experience on 2 fallow bucks and 3 roe bucks in a RWS HIT bullet scenario at similar impact velocities and with similar outcomes. Everything ran 40-100 meters.
I also shot 8 animals during the same period with the Hornady SST, and the RWS Speed Tip Professional. A red hind, a red spiker, a 3 fallow does, and 2 roe deer. Cup and core all the way. 100% bang flop or took two steps and died.
I have not used a bonded or formation bullet since I lived in Australia. I used to shoot the 168 Accubond in my 30-06 Tikka T3 Varmint. Shot hundreds of kangaroos with it, a few deer and a few pigs and used it to kill an injured bovine for a farmer. It shot very well, and on kangaroos it mostly gave a bang flop, but on deer and hogs they usually got 50-100 yards away.
When I think back of my hunting career of the past 38 years, I would 100% rather hunt with a cup and core bullet than a deformation bullet or a solid copper bullet.
Here in Germany we are stuck on federal lands with lead free bullets, but I really hate them.
At your distances I would select the bullet that shot best in my gun, with preference toward the heaviest bullet. As impact momentum will be better even if velocity is not.
Hornady loads a 143 ELD-X and a 129 SST in factory for that cartridge.
Nosler loads the 140 Grain grain accubond in factory ammo.
Swift does not load the Scirocco or A-Frame in the 6.5 PRC that I see.
