Here is a picture of a Barnes 6.5 120gr TSX I recovered from the dirt bank behind my 100yd target. It is about 1/2" across & still weighs 120 gr on my scale. It was launched from my 6.5-06 at 3235fps which means it struck the dirt bank at about 2970fps. This is a very desirable mushroom shape with the 4 petals being very evident. None broke off. Perhaps bullets striking game will not be as perfect a mushroom . Striking dirt is brutal to a bullet..

340 gr Rhino Solid Shank from .375 H&H recovered from giraffe opposite humerus-scapula joint. I weighed it the same evening: 339 gr. Need the 2.5x calibre expansion to prevent exit as the shot on giraffe is upwards over the tree line.
300 gr Peregrine from .375 H&H recovered from Cape buffalo opposite skin- broke both shoulders and cut the top of the heart. That is what "mush-rooming" looks like. 98% weight retention.
I am looking for the photo of the 500gr Peregrine VRG-2 solid from a .458 3" Express that killed 5 elephant with frontal brain shots, taken after the first shot. They reloaded it 4 times for four more of the same. Peregrine is keeping it as a demonstration piece.
I love the pictures of these bullets of obvious quality . They do work!! Thanks Andries, beautiful.
Sometimes I think the homogeneous consistency of dirt creates a more consistent and easier rate of expansion and not as sudden as the diverse objects inside an animal like skin, then tendons and suddenly the radius of a shoulder bone then meat and then a angled rib, etc.
I agree very likely. Ballistic gelatin also does not tell the whole story. As another thought a 6.5 129gr Hornady bonded bullet was shot into this same mound of dirt ( sifted, no rocks ) at about 60 FPS slower than Barnes TSX. It peel back like a banana & now weights 62grs. Quite a difference.
That peeled back 150gr Interbond from my son's .308W into the black wildebeest's shoulder at 260+ something yards broke all the bones and killed perfectly, but for heavier animals at 70-120 yards it is too light weight - he used it only because he knew the distance will bring impact velocity down to about 2,400 ft/sec. He knows the trajectory well and the Karoo plains game are never closer than 220 yards and mostly are light boned - the black being the heaviest, so he knew the bullet would behave well.
Had he been hunting the much heavier blue wildebeest at the shorter ranges up north where I live his choice will be 180gr PMP Pro-Amm impacting at 2,400 ft/sec and the result will be similar. He has not bought into premium bullets yet but only because he has a large stash of the Interbonds for the light stuff he hunts in the Karoo. I made the shift to Peregrines 18 months ago starting with the .416 Rigby and will never use anything else again in any calibre - like you and the Barnes. In the .303 Brit I use 168gr VRG-3/4.
Of course the TSX and TTSX are available here and have some followers, but they are expensive being an import and the silly buying power of our Monopoly money, so the locally manufactured Rhino series, GS Custom and Peregrines hold the market.
Interesting, that most shots for your son are 220 yrds & over & I take most of mine under 200. I understand that the Barnes are an import for you making them more expensive as the Peregrines are more expensive to me.. Seems we have opposite but similar situations.
Don't know if you've seen my Ruger stainless RSI 6.5x55. 18 1/2" Bbl. Very accurate. One of my favorite's. Of course I have several Favorites.
Give my best to your family & in case I forget , Merry Christmas & Gd bless all. Dom
Thanks for the good wishes Dom - may you and your family also have a peaceful day.
The Great Karoo... shooting distances are rarely below 200 metres and mostly at 250. look at the sparse vegetation:
https://www.bullet-behavior.com/forum/actual-bullet-behaviour/308w-hornady-150gr-interbond-vs-black-wildebeest
This photo is not in the Karoo but near Kruger National Park. The Beech 1900 businessliner belongs to a friend of mine.