I have tested loads using IMR4831 and 180g TTSXs and this combination seems to be showing exceptional promise - 3 of the 5 loads I tested went sub-MOA, with one load 4% below the max producing a 3-shot group with all holes touching. Unfortunately on that day, my chrono was not picking up the speeds. As such, I will be retesting the 3-MOA loads.

However, the max load I am using was 63.0 grains based on Quickload data. This max load seems overly conservative as it is below the max loads for many other 180 g bullets,including the Swift Scirocco (max load of 66.3 with IMR4831) - a bullet that has the same, if not slightly lower, max loadings as Barnes Bullets. To see this compare Barnes #4 data with the Hodgdon online data for 180 graines.

If you've used this combo (180g TTSX and IMR4831 in a .300 WSM), what have been the max charges and/or max velocities you have SAFELY reached?

W 780 was actually designed for the WSMs and SAUMs.
It is a bit faster than 4831 and will meter through a measure much better as it's a small ball design.

IME you can use any 168 or 180 gr data with TSXs, as the grooves relieve any pressure concerns.(based on experience with the 30-06, 300 H&H and 300 Winmag.)

Barnes actually suggests RL15 and W760 as best in the 300 WSM w/the 168 TSX. They claim 3000-3100 fps.

Big Game and RL 19 with the 180 TSX, 2900-3000 fps.

http://www.barnesbullets.com/wp-content/uploads/2007/02/300WSMWeb.pdf

For 180's RL19 works well as does Viht N550. A max charge of VihtN550 shoots SMOA with 180 Accubombs in my Kimber.

I have a load for one of my 300wsm and 180 gr TSX that I love. I use 67 grains IMR4831. Sierra lists 69 grains max load for 180 grain bullets. I shoot 180 grain sierra pro hunters and 65 grains for practice and they also shoot great. I have another 300 wsm that only likes 180 grain partitions or 200 gr accubonds, I havent shot it for a few years it has 1000 rounds thru it. Have fun!
Darryl