Bore size of 7mm barrel?

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by desertbull, Oct 16, 2010.

  1. desertbull

    desertbull Well-Known Member

    Messages:
    229
    Joined:
    Jul 25, 2010
    http://www.sharpshootersupply.com/bruxbarrels.html

    I want to order one of these barrels for my Savage in 7mm WSM. Looking at this chart, it list the 7mm WSM as a .277? Will I be able to shoot .284 (7mm right?) bullets in these barrels without blowing my brains out?

    Sorry, but I'm CORNFUSED AGAIN.
     
  2. Flametop7

    Flametop7 Active Member

    Messages:
    32
    Joined:
    Oct 21, 2009
    Well as far as I know 7mm is .284 unless the gun gods changed something.
     

  3. johnnyk

    johnnyk Well-Known Member

    Messages:
    1,731
    Joined:
    Dec 24, 2001
    Desertbull,

    Rifled bores may be described by the bore diameter (the diameter across the lands or high points in the rifling), or by groove diameter (the diameter across the grooves or low points in the rifling).
    Differences in naming conventions for cartridges can cause confusion; for example, the .303 British is actually slightly larger in diameter than the .308 Winchester, because the ".303" refers to the bore diameter in inches, while the ".308" refers to the groove diameter in inches (7.70 mm and 7.62 mm, respectively).
    Hope this helps. JohnnyK.
     
  4. str8shoot

    str8shoot Well-Known Member

    Messages:
    161
    Joined:
    Jul 27, 2010
    They just made a mistake on their website. It says 7mm (.277) instead of 7mm(.284). They are all 7mm(.284) cartridges listed.
     
  5. James H

    James H Well-Known Member

    Messages:
    504
    Joined:
    Jan 15, 2006
    .277" is the most common bore diameter for a 7mm although Brux 7mm barrels are .276".
    FYI 7 millimeters converted to inches = .27559".

    Standard 7mm groove diameter is .284"

    James
     
  6. desertbull

    desertbull Well-Known Member

    Messages:
    229
    Joined:
    Jul 25, 2010

    OK, I can buy that, but then why did they list all of their other barrels in standard American barrel designations (.308, .257, .243) and they don't even list a .270 Winchester as a standard cartridge? What kind of a barrel MFG makes barrels for 6mm but not for a .270 Winchester?
     
  7. J E Custom

    J E Custom Well-Known Member

    Messages:
    7,307
    Joined:
    Jul 29, 2004
    Some barrel makers give you the land diameter and others give you the groove diameter, and
    some give you both.

    The ones that give you the land or both diameter's are normally cut rifling and they are telling
    you how deep the grooves are. (.284 groove Dia. and a .277 land Dia. = .0035 groove depth, or
    three and one half thousandths).

    But just to make sure I would call them and verify that it is for a .284 bullet.

    J E CUSTOM