Off the lands

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by GTS, Sep 22, 2003.

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  1. GTS

    GTS Member

    Apr 23, 2003
    could someone tell me how far off the lands I should be with a 7-300wby with 168gr. MK's. Thank you
  2. BountyHunter

    BountyHunter Well-Known Member

    Jun 13, 2007
    Two things to consider.

    1. OAL and will it fit in magazine if you have one.

    2. What does your gun like with the acceptable level of accuracy you require?

    Sierras like (as a general ruleto be no more than touching and as far off as .045. Only way to know is to shoot it and find out what it likes.

    do you load development if not already and shoot groups starting at touching and come back at .010 intervals to find area and then fine tune from there. Know what your max oal is with mag also.

  3. a.JR

    a.JR Well-Known Member

    May 28, 2003
    Had good success with the #1930SMK and i always start testing with the bullet inserted in the lands.Try a case with enough clearance to allow a slip fit from bullet to case neck,insert dummy round long and chamber,take it out a measure AOL(try this a coupla times).If they're the same length, this is the position that the bullet has been pushed back into the case buy the lands.Lenghten this a few thou and you have possitive land engagement,it's a simple mater of in or out 10 to 20 thou from there.With this type of bullet i have found no gain past 20 thou out,except in one case it was .250 out,but if you don't try you'll never know.UNLESS you are very fussy with bullet batching to develope a load in the "touch" possition will negate some of what you will learn because the differences in ogive lengths(this bullet can vary up to 10 thou in it's possition) so some will touch and some won't . Test powder and primers with it engaged ,it will be at the high in pressure in this possition and can only go down if you jump the bullet.This bullet really responds to equalising the bearing surface ,if you want to know how to make the tool ,email..JR..Jeff Rogers