Wes, I thought you'd like to see a few sources on average barrel life. Your experiences are in a different world from my own and most others:
www.benchrest.com/forums/showthread.php?t=44666
answers.yahoo.com/question/index?qid=20090606214449AAWRAqY
newsgroups.derkeiler.com/Archive/Rec/rec...008-08/msg00881.html
Barrel life's a relative thing as several posts have mentioned. Unclenick's reference to Sierra Bullet's tests pretty much duplicate what Sierra's former head ballistician, Martin Hull, told me back in the 1960's. He rebarreled their rail guns used to test bullets for accuracy at about 3000 rounds. There's a formula that predicts that I'll cover later. Top highpower match rifle shooters would rebarrel their. .308 Win.'s at about 3000 rounds, but didn't want to go to the Nationals with more than 1500 rounds through one. Their 30 caliber magnums (.30-.338, .300 Win. Mag., etc) barrels would last about 1200 rounds. I had a tack driving .264 Win. Mag. in the late 1960's that lasted 640 rounds before it went from 2/3rds to 2 MOA at 600 yards in three shots.
Regarding those "reference" bullets Unclenick mentioned Sierra uses to test their barrels with really are super accurate. Sierra used to call them "standards" and the best of their 30 caliber ones would shoot in the ones and sometimes the zeros; one 10-shot group after another. When located in California, Sierra used to sell these "standards" in plain brown boxes with 1000 bullets in each one. They still had the sizing lanolin on them and weren't polished bright and shiny; that's how they're tested. These were taken right out of the pointing machine as a hand full were grabbed and seated in pre-prepped charged cases for testing. As long as the test groups were under 2/10ths inch, a special barrel would catch them, then they'd be packaged and taken to big highpower rifle matches to sell to competitors. Accuracy wise, they shot 1/3rd better than the bullets sold in green boxes. These bullets were the ones used to win most of the highpower matches and set most of the records until they quit selling them when they moved their plant to Missouri. I've still got some of those 30 caliber 168, 180, 190 and 200 grain "standards."
A formula I've used for years to calculate barrel life is as follows: 1 grain of powder for each square millimeter of the bore's cross sectional area will result in about 3000 round of accurate life for that cartridge. I think "bore capacity" is also the same thing; a 30 caliber barrel has a bore capacity of about 45 grains. So, a .308 Win. with about 45 grains of powder will get 3000 rounds of accurate barrel life. Double the charge weight for a given bore diameter (twice bore capacity) and you'll get 1/4th the barrel life; a 30 caliber magnum burning 90 grains of powder will get only 750 rounds of most accurate barrel life. So far, this has worked well for competition. Double the number for hunting accuracy and quadruple it for service rifle combat accuracy.
Wes, a lot of this is relative, and I have no doubt I can take any of my rifles and go 15 to 20,000 rounds, but after something under 5 to 8,000 its not likely I'll be posting target results.
zfk55
