A while back I was reading an article on this forum that I think Kirby Allen wrote about suggested powders to use in the overbore cartridges, like the 7RUM. I can't find it now, but it made an impact in my brain, because I shoot a 7rum, and want to get the most barrel life out of it as possible. If I am correct, the article stated that in order to get the maximum barrel life out of a cartridge like the 7mmRUM then it was suggested to use a very slow spherical powder. I use US869 in mine, and have been since it was new, I have 617 rounds through my barrel now, and I am still very happy with the results, I am getting. Does it make a difference in throat erosion if you use a spherical powder, vs an extruded powder?