For what it's worth my first 1000 yd BR rifle was a 6.5 x 284. It erodes the throat .010" per hundred rounds. I sold it with 800 rounds through it with the throat having moved .080". That barrel had maybe 200-400 more rounds of accuracy life, but 1k BR is hard on barrels. I also had a 7mm Rem Mag SS Sendero that moved the throat .040" in 400 rounds in the days when I shot five shot groups in all hunting rifles. I replaced that with a Sendero in 300 Win Mag that had about .020" erosion in 800 rounds but I babied it and only shot three shot groups. My 1K BR rifle in 300 WSM had around 800 rounds through it when I sold it and IIRC it had around .040 of erosion.
Theee is no way around it. The more overbore a chambering is the shorter the barrel life. I know of two possible exceptions. The 7mm STW seems to have better life than the 7mm Rem Mag and the 6mm Rem seems to have better life than the 243 Win. It's thought the short necks of the 7mm RM and the .243 cause more erosion due to the turbulence point being outside the neck.
That's another advantage of the 30s and 33s over the 6.5s and 7s. I used to have a chart to determine the relative overbore-ness of a given chambering to help predict barrel life. Bore diameter squared times 1000 was one ballistics experts idea of the max efficienct case capacity for a given bore size. A .308 bore chambering works about to about 95 grains. I don't know if that formula is gospel on max efficient case capacity, but it does allow us to see the relative bore diameter to case capacity ratio.
A 300 Win has 90 grains of case capacity, making it 94.7% of the theoretical max efficient case capacity. A 338 Edge (116 grains capacity IIRC) is 101.7%. A 300 RUM is about 120%. A 7mm RM is about 100%. A 6.5 x 284 is about 102%. This means a 6.5 x 284 barrel ought to last as long as a 338 Edge barrel and a 7mm RM barrel. A 300 Winny beats them all in barrel life. Now don't take all this as gospel, but it might be a useful general guideline.
Theee is no way around it. The more overbore a chambering is the shorter the barrel life. I know of two possible exceptions. The 7mm STW seems to have better life than the 7mm Rem Mag and the 6mm Rem seems to have better life than the 243 Win. It's thought the short necks of the 7mm RM and the .243 cause more erosion due to the turbulence point being outside the neck.
That's another advantage of the 30s and 33s over the 6.5s and 7s. I used to have a chart to determine the relative overbore-ness of a given chambering to help predict barrel life. Bore diameter squared times 1000 was one ballistics experts idea of the max efficienct case capacity for a given bore size. A .308 bore chambering works about to about 95 grains. I don't know if that formula is gospel on max efficient case capacity, but it does allow us to see the relative bore diameter to case capacity ratio.
A 300 Win has 90 grains of case capacity, making it 94.7% of the theoretical max efficient case capacity. A 338 Edge (116 grains capacity IIRC) is 101.7%. A 300 RUM is about 120%. A 7mm RM is about 100%. A 6.5 x 284 is about 102%. This means a 6.5 x 284 barrel ought to last as long as a 338 Edge barrel and a 7mm RM barrel. A 300 Winny beats them all in barrel life. Now don't take all this as gospel, but it might be a useful general guideline.
