general rule is ( following Vaught )
3 factors
mecanical erosion ( sand blasting )
thermal effect
plasma effect
coarse tubular powder as 5010 ( not in production now I think ) that a good powder ( SD ) but grain of powder seem to make sand blasting in the throat
"hot" spherical powder , some ball powder ( very hight rate in nitro ) are very hot when they burn as example some old lot of SP7 ball powder ( french made powder )
are so hot that you can see throat erosion after 400 rounds in 308 WIN slow fire ( not really a wild wildcat the 308 win )
now SP7 is more quiet by adding graphite but that a durty powder ( too much graphite )
some other facts seem right :
machine gun firing rate increase steel skin temperature up to resistance specs and you get very fast wear / erosion .
long neck with right ( sharp )shoulder angle are better for throat life , powder burn in neck not in throat , that seem logic
I am interesting to get other information on powder / barrel life too
good shooting
DAN TEC