Thread: Is it Pressure or Powder Capacity?

I borrowed a borescope off a mate in the weekend and have been inspecting all my rifle barrels.

This morning I happened to pick up my 25-06 and was surprised to see the first 30cm of the barrel looking fcuked.
Long heat cracks, rough as hell, and bugger all rifling left in the first 3cm!
This rifle has shot under 1000 rounds (about 870), and I'll be the first to admit that I've been running quite hot loads... 85g Nosler Ballistic Tips at 3600fps, 100g NBT at 3400fps and 120g Speers at 3170fps.
I'm on average running 59-60gr of Vitovori N160 which is a lot of powder for a .257" bore (hence 25-06 is known as an overbore cartridge). The cases are only lasting me 4 reloads before I have to throw them....and require trimming after each firing....so I know they are at high pressure (but not flattening out primers).

Therefore my question is this:
Is it the amount of powder burnt that causes barrels to wear out or is it the pressure/'hotness'?