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Thread: Bore riding bullets??

  1. #1
    Boolit Buddy
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    Bore riding bullets??

    So on bore riding bullets, is a bad for them to be engaged to some degree by the rifling? If so how much is to much? What issues dose it cause?

  2. #2
    Boolit Master Ozark mike's Avatar
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    Id set em back .005 but i have limited experience on this topic
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  3. #3
    Boolit Master Dapaki's Avatar
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    Such a simple question with SO MANY answers!

    Example: My 7mm-08 loves 130gr cast boolits, I GC & PC them then load them so they just kiss the lands. Its a Handi so the OAL matters little. Pressures look GREAT, primers are still rounded on the edges and Im getting a touch under 2k for velocity.

  4. #4
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    If they don't stick in the bore when you take the shell out without firing don't worry. If they stick and are accurate, always fire the shell in the chamber!
    Wayne the Shrink

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  5. #5
    Boolit Master
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    I've had some that were difficult to chamber and they still shoot well.

    FWIW, I usually determine where the lands are by 'coloring' the bullet with a Sharpie. When my bullets are sized to just fit in the bore the thickness of the Sharpie makes them difficult to load.

    I use a nose size die to get the bullets just right. The bullets touch the bore and then I seat the rear portion so it lightly engraves as well. Best bullet shapes for this have a tapered portion from the bore riding section to the first drive band.

  6. #6
    Boolit Master RU shooter's Avatar
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    Quote Originally Posted by Wayne Smith View Post
    If they don't stick in the bore when you take the shell out without firing don't worry. If they stick and are accurate, always fire the shell in the chamber!
    Pretty much sums up how I do it . On a bore riding bullet like the Lee 30 cal 170 fn let's say the nose portion needs to be in contact with the lands. When you chamber a loaded round and extract it you should be able to see a light scuff mark made by the lands the whole way around
    The dia. Of the nose portion don't need to be deep but contact is needed to hold the bullet straight on it trip down the barrel on bullets with a shorter nose like the Lee 150 or 160 rn its more balanced the rear is longer than the nose so not as important . But if it chambers and extracts without pulling the bullet it's good even with deeper engraving from the lands
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  7. #7
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    Hmmm. How many of the above posters really know what a "bore riding" bullet is and how it is supposed to fit? A couple?FWIW a bore riding bullet has a section that does not engage the rifling, it rides in the bore...
    My Anchor is holding fast!

  8. #8
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    Quote Originally Posted by mdi View Post
    Hmmm. How many of the above posters really know what a "bore riding" bullet is and how it is supposed to fit? A couple?FWIW a bore riding bullet has a section that does not engage the rifling, it rides in the bore...
    Very true, but, obturation will cause the nose to be lightly engraved by the rifling.
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  9. #9
    Boolit Master Oldfeller's Avatar
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    Why this confusion continues is the use of the term "bore riding" bullets --- these are "land top riding" bullets.

    If you used the right words folks would understand them better.

    A "bore riding" bullet is a throat-fitted loverin style slug that is insta-sized by acceleration in the throat (by obturation slug up) ..... followed by push sizing the throat sized slug down into the fully engaged rifling to become a true bore riding projectile.

    (Mann called them putty plugs and it explained many of his "short barrel test" deformation results)

    And, if you think the "reduced nose diameter" even exists past the instant of ignition I suggest you stop a low velocity bullet or two in water jugs and look at the full depth rifling marks on that "reduced nose diameter".

    Last edited by Oldfeller; 06-25-2020 at 09:14 AM.
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  10. #10
    Boolit Master Maven's Avatar
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    I tried to post about this yesterday, but got caught amidst the server changeover. To wit, bore riding bullets are also know as two diameter bullets as mdi suggests. If the bore rider in question fits [your gun] correctly, it will be engraved the rifling, lightly or deeply, depending on the nose diameter of the bullet and the depth of the rifling. I suppose it's up to the shooter to determine just how much engagement is wanted.

  11. #11
    Boolit Master Bad Ass Wallace's Avatar
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    My best example of a 'bore rider' is the 375gn boolit for my 38/55. The entire nose contacts the rifling and it shoots great!

    Hold Still Varmint; while I plugs Yer!

  12. #12
    Boolit Grand Master Good Cheer's Avatar
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    My favorite is for a 45 Colt rifle.

    The crimp groove to front of first land is to SAMMI specs to kiss the rifling.

  13. #13
    Boolit Master
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    Quote Originally Posted by Oldfeller View Post
    Why this confusion continues is the use of the term "bore riding" bullets --- these are "land top riding" bullets.

    If you used the right words folks would understand them better.

    A "bore riding" bullet is a throat-fitted loverin style slug that is insta-sized by acceleration in the throat (by obturation slug up) ..... followed by push sizing the throat sized slug down into the fully engaged rifling to become a true bore riding projectile.

    (Mann called them putty plugs and it explained many of his "short barrel test" deformation results)

    And, if you think the "reduced nose diameter" even exists past the instant of ignition I suggest you stop a low velocity bullet or two in water jugs and look at the full depth rifling marks on that "reduced nose diameter".

    First, bore riding is a bullet with a nose that rides on the bore, ie, touching the lands but not engraved into the grooves. It 'rides the bore' as it is chambered. The bore is defined by the 'tops' of the lands.

    Second, yes, the bullet should upset into the grooves when fired.

    The bore riding portion is to allow a long, heavy bullet to be chambered in a rifle that has a short neck and/or throat. The forward section needs to be sized closely to the bore to make sure it stays 'straight' on loading. That way at least you have a chance that it will upset evenly into the grooves.

  14. #14
    Boolit Master Dapaki's Avatar
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    Well, well, well, learn something new everyday! I was always under the impression that a 'bore rider' was a boolit that the nose was smaller than the lands distance and the driving band is where you kissed the lands when loading the cartridge?

    This .310 runs .297 on the nose and just slides over the lands.

    Click image for larger version. 

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  15. #15
    Boolit Master
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    My Finn 1935 Model 39 uses Lyman's 314299 sized to .3135 and every so often I'll push one down the barrel and check for any dimensional changes. With the above bullet seated out as far as it can go it will not fit the magazine. Instead I let the bullet sit on the loading tray or follower and let the bolt push into the chamber.
    In over 3000 rounds have not had any problem too date. But back to the OP's question. When pushing the bullet through the barrel will show mild to moderate engagement but the body of the bullet shows very definite engagement. I'm not trying for world record groups. I usually get 2" groups @100yds. Frank

  16. #16
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    Quote Originally Posted by Good Cheer View Post
    My favorite is for a 45 Colt rifle.

    The crimp groove to front of first land is to SAMMI specs to kiss the rifling.
    What boolit is this?
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  17. #17
    Boolit Master
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    Quote Originally Posted by Dapaki View Post
    Well, well, well, learn something new everyday! I was always under the impression that a 'bore rider' was a boolit that the nose was smaller than the lands distance and the driving band is where you kissed the lands when loading the cartridge?

    This .310 runs .297 on the nose and just slides over the lands.

    Click image for larger version. 

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Size:	16.4 KB 
ID:	264184
    Do both. The bore section touches in the bore and the rear driving bands are engaged into the rifling when chambered.

  18. #18
    Boolit Master Dapaki's Avatar
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    Quote Originally Posted by charlie b View Post
    Do both. The bore section touches in the bore and the rear driving bands are engaged into the rifling when chambered.
    Soooooo, it's a bore rider?

  19. #19
    Boolit Master
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    Quote Originally Posted by Dapaki View Post
    Soooooo, it's a bore rider?
    Yes it is.

  20. #20
    Boolit Master
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    I call 'em bore riders anyway, you do not want the bore rider portion to be loose in the bore, you can test this somewhat by trying the boolit into the barrel from the muzzle end.

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