Recent content by Bart B.

  1. B

    Gunsmithing Barrel Fluting vs Barrel Stiffness

    Mechanical engineers working with vibration issues can calculate how fluted barrels will vibrate at different fundamental and resonant frequencies. 4th order equations used are the same ones used to calculate how much buildings vibrate in earthquakes. Here's some good stuff...
  2. B

    Gunsmithing Barrel Fluting vs Barrel Stiffness

    3 barrel makers told me hammer forged barrel's inner diameter shrink a few ten thousandths under the flutes and button rifled barrels expand the same. Cut rifled barrels change half that much either way.
  3. B

    Gunsmithing Barrel Fluting vs Barrel Stiffness

    Anyone still think fluting barrels makes them stiffer in spite of metal being removed that used to resist bending? Metal on the top half resisted stretching, that on the bottom half resisted compressing.
  4. B

    Gunsmithing Headspace question

    SAAMI center fire rifle chamber, cartridge and headspace gauge dimensions are available as downloads in.... https://saami.org/wp-content/uploads/2019/02/ANSI-SAAMI-Z299.4-CFR-Approved-2015-12-14-Posting-Copy.pdf Look up the cartridge in the table of contents for the page numbers
  5. B

    How were '03 and Garand barrels rifled?

    The barrels used in the USN 7,62 NATO Garands were all broach rifled with the same 1:12 twist used in M14 service barrels. All were air gauged for uniformity and those with groove diameters .3079" or smaller were set aside for match grade rebuilt Garands. Tightest ones gauged .3077" which...
  6. B

    Winchester M70

    DiSimone scopes had the best optics. Al, himself, told me American Optical made the lenses to his specs but decided he couldn't improve over the Unertl mounts he used. I borrowed one, a 1.5" 20X, for a weekend of 1000 yard matches and its images were easily better than my Unertl with the same...
  7. B

    Winchester M70

    Unertl, Lyman, Fecker, Litchert and DiSimone target scopes were always detrimental to (tiny) grouping. Their weight on the barrel changed the muzzle axis vibration frequencies and directions. If they were pulled back then twisted back to the same position for every shot, that helped. If not...
  8. B

    Rifle Scopes The Level Questions Asked

    Yes. Its barrel was 999 yards long.
  9. B

    Rifle Scopes The Level Questions Asked

    I took your post at face value 'cause I'm not smart enough to think between your words. But I shoot my stuff precise enough to resolve about 5/8ths inch windage error at 1000 yards with one shot. And simply multiplied the scope offset by 9 to get the shot offset at 1000; no fancy trig math needed.
  10. B

    Rifle Scopes The Level Questions Asked

    Can a 5 year old understand this to see a 6 degree cant moves impact about 10 inches sideways? Then use trig to calculate his own ammo's bullet impact shift for a given cant angle?
  11. B

    Rifle Scopes The Level Questions Asked

    Yes, you need one if you don't use some other way to keep the cant angle the same for each shot.
  12. B

    Rifle Scopes The Level Questions Asked

    Yes, it does. What trig function calculates the drop difference for a cant angle? Note the line of fire is seldom more than 1 degree above the line of sight in horizontal fire. I edited my post to clarify this.
  13. B

    Rifle Scopes The Level Questions Asked

    It's simple 7th and 8th grade trigonometry using 4th grade math.
  14. B

    Rifle Scopes The Level Questions Asked

    OK, Culpepper, here's the first part in English. Do you understand that bullets drop virtually the same amount at target range regardless of where the muzzle axis points? This is for horizontal line of sight +/- 1 degree vertically. If not, this has to be well understood before going further.
  15. B

    Rifle Scopes The Level Questions Asked

    The horizontal change in bullet impact for a given cant equals bullet drop at target range times the sine of the cant angle. Vertical change is insignificant for the first few degrees.
See more
Top Bottom
Back
Home
Forums
Merch
Alerts