My experience with the Barnes remains limited but positive and I plan to use them more but not always. What I found is they work well over a wide range of speeds and distance. I used the 300g TSX in a 375HH on Blue Wildebeest. First shot was a frontal at 160-180y. That is approaching the limit of what I like with that rifle and load. You want to keep the impact velocity above 2000fps on the TSX or any other expanding bullet in my opinion. With that 375 the limit is about 200y max with the Barnes.
Barnes penetrates well at a wide variety of velocity since it expands less at the slower speeds. Penetrates enough but does less damage at slower speeds. In my case the longer shot at 180y expanded to only 2.0x but still penetrated about 3ft of the Wildebeest and lodged in the paunch. The animal bucked, wheeled, stumbled and ran about 60y and piled up. 1st shot was fatal but we placed two followups for insurance. The 2nd followup was at 60y and hit the neck and was a pass thru. The last was at 10y in the chest and lodged under the skin on the opposite shoulder. That shot expanded to 2.2x and ended things instantly. I was surprised that it did not pass thru. Pic below: The left lower bullet was the 1st shot at 180y and the right one was at 10y. Not that much difference. The 2nd shot was a bit larger than 0.82". That is a big hole.
I am taking several choices with me this next safari. My 7mm/08 will feed on 140g Barnes TTSX, 140g Federal Fusion Tipped, and 150g Swift Sciroccos. All shoot well and to same POI within the planned ranges and out to 400y. I tried Hornady CX Superformance 139g also, but they did not shoot well in my rifle so, I am leaving them home. With my 375HH, I am taking the 300g TSX for Buffalo, and a few 300g A-Frames for other large critters, and a few 250g TBBC for Kudu. I think the key to success has more to do with your marksmanship than with the bullet as long as you place the first shot well and use a quality bullet. All of these are good ones, well proven.
From what I have seen personally, comparing Fusions in 308 and 7mm Mag to Barnes is that the Fusions still penetrate well but seem to hit with more authority and more often than not result in very fast kills. All of mine were pass thru, so I have not recovered any of them but independent tests on ballistic gel shot them to expand to as much as 2.5x out of these rifles. I have taken six large game recently with these including: Nyala, Duiker, Bushbuck, Gemsbok and Impala with 308 and large Whitetail deer with 7mm at ranges from 20y to 202y and all were 1 shot kills and the furthest any ran was 60y. Most (four) were bang flops. Took one buck a few years back with the 250g TBBC and it was a bang flop as well at about 60y.
Counter Point: My son and I are planning a guided Texas Nilgai hunt for 2026 and in talking to the outfitter/guide, about rifles and ammo, he refused to allow me to use my 7mm mag saying it is too small and lacking penetration?? WTF. He favored the 375HH and said minimum was caliber allowed was 300 win mag. I have two 375HH rifles and told him I would bring the 300g TSX ammo and he said "DO NOT USE TSX". That was a bit of a surprise. I suspect that his bias is because many of his clients are taking shots out to about 300y in that big wide open Texas terrain. That is fine with a 300 mag but the big fat 375 has slowed to 1840fps at that range. So slow that the Barnes bullet does not expand much if at all and may simply pencil thru. Result is long tracking jobs or lost game.
After a long discussion with him, he suggested either TBBC (Which I have a bunch of for the 375) or Nosler Accubond. We plan to take both a 375HH using that load and a 338 RCM loaded with 200g Accubonds which will remain effective out a little further if needed. So, while I have found the Barnes coppers to be very effective, they do have their limits and in some cases may not be the best choice.
As others say if you plan to use the TSX or TTSX, keep the speed up within the planned range you will be shooting. Either reduce the range or use a lighter bullet to get better velocity at the POI and you should be pleased with the result.