The Barnes TTSX or LRX are excellent hunting bullets, the TSX works too,but it's of a tougher construction, and slower expansion makes it even more dependent on velocity.
In my opinion there is no better hunting bullets available for short to medium range hunting, clean and quick kills, with little meat damage, good terminal effect, and incredible penetration, never found a projectile left in a animal yet, even with my 308 broadside shots on Moose.
For long range hunting more fragnible bullets will perform better like a A-max, Berger hunting, Accubonds etc.
There is also one more thing you must understand about these bullets, they are dependent on velocity or a lot of resistance to deliver proper terminal effect and expansion, and the lighter weight bullets will usually perform better in any caliber, with some moderation on heavy game, a long with the fact that they are longer then a normal lead core bullet.
Below 2000-2200 fps the performance of the bullets will drop drastically, the expansion will be less and the terminal effect will lessen, witch can lead to slow kills at longer ranges.
I do suspect a lot of shooters, look first at the bc and choose the heaviest bullets for they're caliber , at fairly low velocity, witch is counter productive to the design of these bullets, and the length can some times give issues with the twist rate.
Witch both will leave the user with some of the undesirable results i have read a lot of times.
These bullets has they're limitations, but when used the right way they will perform admirably from my experience.
This is just my personal experience though,have shot around a 100 deer and some Moose with Barnes ttsx,lrx and tsx.
So my hunting is most likely more then one shot a year, or i would be quite seasoned by now ^^
The gmx i have no experience with.
However i have used/tried, Partitions,Accubonds, A Frame, Scirocco, Game king, Oryx and Interbonds.
And for use out to 3-400 meters depending on the caliber Barnes is my choice at least.
My favorite big game bullets currently, is the 284 145 gr lrx, while i use 180 berger hybrids for target shooting.
As the Barnes bullets usually shoot well with some jump, the accuracy has been good.
For long range shooting, if your looking for solid copper bullets only, you can find very consistent lathe turned copper bullets, that work very well with the proper twist rate, they normally cost a lot though and is often for bigger calibers.
If your just looking for target bullets that will perform well at long range, Berger, Lapua, SIerra and Hornady.
Provides that for a reasonable price and with bullets designed for the task.
There are also some good custom bullets out there, like JLK, Matrix and Cauterico for a price.