Quantcast

Rifle Chamber Jargon Question

Discussion in 'Gunsmithing and Repairs' started by carnaby, Apr 25, 2019.

  1. carnaby

    carnaby Member

    Joined:
    Feb 25, 2004
    Messages:
    1,375
    Location:
    Bellingham, WA
    Does anyone use a name for the section of the rifle chamber between the end of the neck and the start of the freebore? I've heard *step*, *forcing cone*, and nothing else. Neither seems right, especially forcing cone... what does that little shoulder force?

    Every other part of the chamber has a well enough defined name. If it doesn't have one, it should. Maybe *neck step*, *neck shoulder*, *freebore step*, *throat step*, or ...?
     
    LoonWulf likes this.
  2. LoonWulf
    • Contributing Member

    LoonWulf Contributing Member

    Joined:
    Jul 3, 2010
    Messages:
    11,617
    Location:
    Hawaii
    Throat, freebore usually is kust kinda an intentionally long throat. .... From my understanding anyway
     
    milemaker13 and boom boom like this.
  3. carnaby

    carnaby Member

    Joined:
    Feb 25, 2004
    Messages:
    1,375
    Location:
    Bellingham, WA
    I don't think you understood my question. I'm looking for the name of the step in diameter from the neck to the freebore. The diagram below calls it the *second shoulder*.

    Chamber2.jpg
     
  4. GBExpat

    GBExpat Member

    Joined:
    Nov 5, 2007
    Messages:
    6,169
    Location:
    Rural, far beyond the beltway, Northern Virginia,
    Interesting. I learned long ago that the "Throat" is composed of the Freebore + the Leade (a term not even included on that diagram). It appears that the Leade is labeled as the Throat, above.

    Perhaps it is a European (CIP) rather than an American (SAAMI) thing. :)
     
    milemaker13 likes this.
  5. 243winxb

    243winxb Member

    Joined:
    Jul 7, 2004
    Messages:
    11,546
    Location:
    USA
    SAAMI - Key wording- tapered portion
     
    boom boom and GBExpat like this.
  6. carnaby

    carnaby Member

    Joined:
    Feb 25, 2004
    Messages:
    1,375
    Location:
    Bellingham, WA
    Look at the diagram in my last comment. The thing labeled "second shoulder" is all I am interested in. I already know the shoulder, the neck, the freebore, the leade, and the throat.
     
  7. 243winxb

    243winxb Member

    Joined:
    Jul 7, 2004
    Messages:
    11,546
    Location:
    USA
    THROAT

    Screenshot_20190425-220643.jpg
     
    Last edited: Apr 25, 2019
    milemaker13 likes this.
  8. carnaby

    carnaby Member

    Joined:
    Feb 25, 2004
    Messages:
    1,375
    Location:
    Bellingham, WA
    It's definitely not the throat. The throat is synonymous with the leade, according to the SAAMI page you linked to. This is the section BEFORE the freebore and leade/throat. It is very short, cut at a 45 degree angle. In your drawing it starts at 2.025" and ends at 2.0488" for a total of 0.0238". The throat starts at 2.1388 and ends at 2.3025. It's not the throat and it's not the free bore. It doesn't have an official name I don't think.
     
  9. LRDGCO

    LRDGCO member

    Joined:
    Jul 11, 2018
    Messages:
    689
    It's called a leade and is the conical transition or step between the throat and the rifling. It may be cut to varying degrees of taper. While such taper is not terribly important in modern high pressure rifles, it is, for example, a subject that occupies much "discussion" with the paper patch community.

    For more:
    https://bisonballistics.com/articles/an-introduction-to-rifle-chambers
     
    boom boom likes this.
  10. carnaby

    carnaby Member

    Joined:
    Feb 25, 2004
    Messages:
    1,375
    Location:
    Bellingham, WA
    Ugh! You guys need to read closer. Please make sure you understand my question before answering. IT IS NOT THE THROAT
    IT IS NOT THE LEADE
    IT IS NOT THE FREE BORE

    It is the section just before the free bore at the very end of the neck.
     
    <*(((>< likes this.
  11. MihiT

    MihiT Member

    Joined:
    Mar 12, 2019
    Messages:
    159
    the end
     
  12. Blue68f100

    Blue68f100 Member

    Joined:
    May 25, 2011
    Messages:
    5,880
    Location:
    Piney Woods of East Texas
    You are referring to where the chamber neck ends and transitions into the lead. I've always considered this part of the neck. Since it's beveled I can see why it's referenced to as a second shoulder. But it's not the shoulder, just a angled cut for transitioning to the leads. Not sure why they are calling it something it's not.
     
    243winxb likes this.
  13. LoonWulf
    • Contributing Member

    LoonWulf Contributing Member

    Joined:
    Jul 3, 2010
    Messages:
    11,617
    Location:
    Hawaii
    Go ask @MachIVshooter lol I think he's about the most likely to know what term your looking for, cause I sure don't.
     
  14. boom boom
    • Contributing Member

    boom boom Moderator Staff Member

    Joined:
    Sep 24, 2007
    Messages:
    4,777
    Location:
    GA
    LoonWulf and <*(((>< like this.
  15. MachIVshooter

    MachIVshooter Member

    Joined:
    Aug 11, 2005
    Messages:
    16,549
    Location:
    Elbert County, CO
    The step ahead of the freebore area is a nameless feature.

    This is the correct answer:

    Free bore means exactly that, a part of the bore in which the bullet is "free" of contact with the bore. Any distance ahead of the case mouth & before the leade is free bore. The leade is the transition from free bore into rifled bore, which may include a smooth groove diameter or tapered section.
     
    milemaker13 and LoonWulf like this.
  16. LoonWulf
    • Contributing Member

    LoonWulf Contributing Member

    Joined:
    Jul 3, 2010
    Messages:
    11,617
    Location:
    Hawaii
    :D:thumbup:

    I learned something!
     
  17. carnaby

    carnaby Member

    Joined:
    Feb 25, 2004
    Messages:
    1,375
    Location:
    Bellingham, WA
    Nameless feature is what I thought. I would like it to have a name. Possible, MachIVshooter, that you have a nickname for it? Second neck and forcing cone are unsatisfying.

    I already know exactly what all the named features are and I understand their definitions perfectly well. This is why I would like the nameless feature to have a name because it does come up in discussion and you can see the trouble. It took 10+ replies before someone finally knew what I was getting at, and even then you lectured me on free bore and leade/throat.
     
  18. Jim Watson

    Jim Watson Member

    Joined:
    Dec 24, 2002
    Messages:
    27,499
    The step down from neck diameter to throat diameter is the Chamber Mouth, Mirror image of the case mouth.

    Terms are slippery on the internet, but I take the Throat to be the cylindrical section, usually at or slightly above groove diameter, from the Chamber Mouth to the origin of the rifling. It is only Freebore if it is longer than its diameter. I call the taper from throat into full height of lands the Leade.
    Others, many here above, use Throat, Leade, and Freebore interchangeably. OK.
     
    carnaby and boom boom like this.
  19. MihiT

    MihiT Member

    Joined:
    Mar 12, 2019
    Messages:
    159
    Case-to-throat transition/step/shoulder thingee.
     
  20. GBExpat

    GBExpat Member

    Joined:
    Nov 5, 2007
    Messages:
    6,169
    Location:
    Rural, far beyond the beltway, Northern Virginia,
    Short and catchy! I like it! :)
     
    carnaby and OrangeCat like this.
  21. GBExpat

    GBExpat Member

    Joined:
    Nov 5, 2007
    Messages:
    6,169
    Location:
    Rural, far beyond the beltway, Northern Virginia,
    How'bout "Nameless Feature". :)
     
    carnaby and milemaker13 like this.
  22. <*(((><
    • Contributing Member

    <*(((>< Contributing Member

    Joined:
    Feb 1, 2013
    Messages:
    2,751
    "Angle Where the Fun Begins" AWFB for short.
     
  23. LoonWulf
    • Contributing Member

    LoonWulf Contributing Member

    Joined:
    Jul 3, 2010
    Messages:
    11,617
    Location:
    Hawaii
    Im inclined to call it "Meh" lol
     
    Last edited: Apr 26, 2019
    carnaby, milemaker13 and GBExpat like this.
  24. carnaby

    carnaby Member

    Joined:
    Feb 25, 2004
    Messages:
    1,375
    Location:
    Bellingham, WA
    I like all these answers:)
     
    GBExpat likes this.
  25. Mowgli Terry

    Mowgli Terry Member

    Joined:
    Dec 6, 2016
    Messages:
    1,322
    Location:
    Tennesse-former Confederacy
    How about a contest to name this thing. The prize would be a Yugo.
     
    LoonWulf and carnaby like this.
  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice