Recent content by Bart B

  1. B

    What am I doing wrong with sizing brass?

    I suggest you use a black Magic Marker coating all of a cartridge, let it dry then chamber it closing the bolt. Eject the cartridge then see where the dye got rubbed or scraped off. Those places show where the cartridge is too big for the chamber
  2. B

    Ladder testing at 1k- Detailed article and video

    Looks like you started with a clean barrel. First few shots from a clean one start 20 to 30 fps slower then settle about the average. "Season" the barrel with 2 or 3 rounds before testing them. I suggest shooting at least 3 shots per test load. 5 is better. All shots after the first one of...
  3. B

    Full Length or Neck Only; What's Best Resizing for Accuracy?

    One thing in favor of 30 caliber bullets is their long, heavy ones are easier to make well balanced. They have higher BC for their weight and and least amount of jump off the bore axis as they clear the muzzle. Some of us remember the problem Sierra had with their first heavy 7mm match bullets...
  4. B

    Full Length or Neck Only; What's Best Resizing for Accuracy?

    Then we're using and doing different stuff. US military method in 30 caliber rifles with their throat erosion gauge let it go in 1/10th inch further about every thousand rounds. .001 inch every 10 shots.
  5. B

    Understanding cartridge efficiency

    Yes, a case manufactured to SAMMI specs should have a standard weight and therefore a standard volume if they thought it was important. But the other variables in the barrel and ammo consumers use would make it meaningless. SAAMI test barrels with tight specs would have to be used to...
  6. B

    Understanding cartridge efficiency

    If a standard volume is desired, first use case outside dimension specs to calculate a weight base using cartridge brass specs. One spec says cartridge case brass weight is .308 pound per cubic inch. Second, subtract case weight from the base weight to get the case volume's weight if full of...
  7. B

    Understanding cartridge efficiency

    I don't think so because case weight comes into the equasion as this data shows PPU case volume average 71.23 grains of water, 185.93 grain average empty case weight. Remington case volume average 69.06 grains of water, 199.63 grain average empty weight. Federal case volume average 69.46...
  8. B

    Understanding cartridge efficiency

    Measuring the case capacity in the one they had? Or some other source? Ask them where it came from.
  9. B

    Understanding cartridge efficiency

    I've never seen any official case capacities listed. Too many variables across all of a given cartridge. The only way one would be valid is to have the case outside dimensions at some standard. SAAMI cartridge case specs for instance. Otherwise, fired cases and resized cases would have...
  10. B

    Understanding cartridge efficiency

    Page 88 in the center fire rifle book: Next page shows velocity and pressure
  11. B

    Full Length or Neck Only; What's Best Resizing for Accuracy?

    It's been mentioned that setting case shoulders back reduces case volume. What about throat wear as bullets seated to the lands increases the case volume behind the bullet? My 308 Winchester barrel throats advance about .001 inch every 30 rounds. 30 caliber magnums about every 13 rounds per...
  12. B

    Understanding cartridge efficiency

    SAAMI has cartridge, chamber, pressure and velocity specs for some wildcat cartridges. Download the center fire cartridge data in the below link. https://saami.org/technical-information/ansi-saami-standards/
  13. B

    Full Length or Neck Only; What's Best Resizing for Accuracy?

    Has anyone actually measured rimless bottleneck case neck centering in the chamber neck when the case is in its firing position? I have and full length sized ones are better centered. Not much difference, a thousandths or so is typical. Cut the barrel off at the chamber mouth so it's able to...
  14. B

    Understanding cartridge efficiency

    There's good evidence that shorter, fatter cases tend to shoot bullets more accurate. And cartridges whose powder charge weights in grains is the same number of square millimeters of bore cross section area shoot most accurately for about 3333 rounds. 40% more powder cuts barrel life in half.

Trending threads

Top