Wonderful insights. I'm a dyed in the wool A-Frame fan but I wondered whether it would be too much of a good thing in a 7x57 for North America and smaller plains game. I've heard wonderful things about Northforks but I'm always skeptical of new things. The significant testimonials have convinced me to try them in the 7x57 to see if I can get a bit better expansion at lower terminal velocities so I don't have to build multiple loads for a rifle.
Provided they're accurate in the rifle chose, I'd use an A-Frame anytime. But I mostly use North Forks bonded cores. They've typically been easier and quicker to find an accurate load for.
Mind you, NF bonded like good brass. Think Lapua or Norma here. The bullets are true diameter and a consistent neck thickness is critical to avoiding the occasional flier. It's not that the flier is that bad, but it screws with my shooting OCD that I spend the extra on brass to maximize accuracy.
I can't tell you how many NF softs I've loaded from various 7mm cals, .308 cals, .375HH and .470NE, nor how many animals they've accounted for.
As for the 7x57, I wouldn't go higher than 160gr in the NF. It's just not necessary with the weight retention of the bullet. My youngest killed a zebra on a quartering too shot using his 7x57 and a 140gr NF soft. The bullet entered just to the right side of the stallions left shoulder, traversed across the top of the heart severing the blood vessels, through the right lung coming to rest under the hide at the back of the right shoulder.
The stallion dropped at the shot. He regained his feet when Jacque's jack russel caught up to it, ran 20 yards and dropped dead. When we gutted the stallion, the heart just rolled out of the cavity attached to nothing. I don't know how the bullet could perform better.
The load for my son's rifle uses IMR4350, I wouldn't be surprised if that worked well for the 160gr bullet too.
This is nothing against the A-Frame. I just typically find somewhat better accuracy and with fewer variations required to get to my NF loads. Again I'll stress you really need to use the better brass. It took me awhile to figure that one out and talking to the owners of NF prior to Jorgen buying them.