Originally Posted by squeezenhope
Trickymisfit, I am interested in your comments as to barrel life. I am not critical, but would like to hear on what you base your opinion. It seems so hard to get a valid true comparison of barrel life, with ALL things being equal. By the way, I have been shooting a .243 Rockchucker since 1972.
first of all my comments were directed towards the .243 Winchester case design, and not the Ackley or Rockchucker. These case are fairly similar except for the shoulder angle (I actually like the rockchucker better than the .243 Ackly). My comments about reaming the .243 chamber with a 6mm Ackley reamer, but using a .243 Ackley headspace gauge are fairly simple. The chamber will clean up nicely, and without a lot of effort. You get the much desired .35" neck length, but like you, I'd have prefered the 30 or even 35 degree shoulder angle. Around my parts a .243 Rockchucker reamer is about as rare as it gets (I don't know that I've ever seen one), but the 6mm Ackley is fairly easy to find. That's why I said to ream the chamber with the 6mm reamer, but cut it short to use the .243 AI gauge.
Barrel life has always been an issue with the .243 Winchester if you shoot a lot of rounds thru it a year. Dosn't load very long and heavy bullets as well as it should due the the excessively short neck length (the bullet ends up being inside the shoulder area, and that ain't a good thing). I guess you could cut the throat excessively long to cure this issue, but then create some others. On the otherhand thse .243 case don't do very short bullets as well as it should, but in most case will get by. But most also shoot with a lot of bullet jump. A 6mm barrel will usually go twice the distance of a .243 Winchester, and the Ackley could be slightly longer (debatable). The problem with the Ackley is that the 6mm Remington case is really about the max capacity for a 24 caliber round without getting into overbore. The Ackley version is into overbore, but not a huge amount like something like a 6mm-06. If you CAD out a standard .243 Win case, you will see that the turbulance points is inside the barrel's throat. Not a good thing! The 6mm Remington's TP is about 20% inside the neck as measured from the lip. Better! The 6/284 actually is slightly better, but suppers from a great overbore condition. The Rockchucker case is about the same as the standard 6mm case (still good). Never quite figured out why Fred settled on that 28 degree shoulder instead of a more common 30 degrees! I'm sure he had his reasons.
I shoot the 6/250AI, and the barrel looks like it's toast in less than 1200 rounds, and maybe gone at the 1000 round mark. It has the Ackley 40 degree shoulder and also the vaunted doghnut issues. The neck comes a tad on the short side (I see necks in the .25" area using .243 Win cases as a parent). I think that had that chamber been cut with a 6mm Ackley reamer, I could have cleaned up .243 cases for an O/L length of 2.00". Giving me a neck length of about .35", and probably an honest 1800 shot barrel life. Plus the .243 Lapua cases are great cases to start out with. I like using the .243 brass as a parent case anyway, because there is a lot less brass displacement during fireforming. Of course the 6BG solves all these issues in spades, and has the desired 30 degree shoulder angle.