20 BR Improved

Discussion in 'Small Stuff--22s, 20s, and 17s' started by martini, May 11, 2018.

  1. L.Sherm

    L.Sherm

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    I wouldn't be afraid to try H4895 either, RL16 was the same as H4350 no speed.
     
  2. martini

    martini

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    Shot the 20 BRAI for groups for the first time Wednesday. I'm got about 1.5" at 200 yards with 40g Vmax bullets and 8208 or RamShot TAC (four shots in 3/4" first shot was 2" away from the group). Need to increase the powder charge a bit as the hottest loads showed the best accuracy. I haven't chrono'd loads yet so I don't know what velocity I'm looking at.
     
  3. martini

    martini

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    About 3600 fps out of a 27" barrel with a muzzle break.

    thanks,

    Randy
     
  4. chuckshooter

    chuckshooter Silver $$ Contributor

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    I'm going to build one of these 20 br's and need a little help with the free bore dimensions . If anyone has a copy of their print they could share with me and tell me what bullet you shoot would be helpful. My goal is to shoot the 40 grain V-Max because I have over 10,000 on hand. Thanks Jim
     
  5. L.Sherm

    L.Sherm

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    Zero freebore would work fine with the long neck of a BR case, .020 max.
     
  6. Terry

    Terry Gold $$ Contributor

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    Zero is the right answer. Had a reamer maker tell me .068 he was wrong. Reground to Zero.
    Places the base of a 55 gr. Berger in the middle of the neck on a BR case.
     
  7. moorepower

    moorepower

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    That case looks kind of like the 5mc2 or whatever they called it with the round shoulder. Probably isn't but it shure looks rounded to me.
     
  8. martini

    martini

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    I don't believe it is rounded like the McPerson cartridges. Regardless, I shot a 1.1" five shot 200 yard group with the barrel (IMR 8208 and 40g Vmax) and like it well enough so that I ordered a second barrel cut with the same reamer for a heavier Savage project. Given that I have a custom sizer die, I don't see the downside to a second barre.

    Randy
     
    Last edited: Aug 11, 2018
  9. CdnHotshot

    CdnHotshot

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    Using IMR8208 with the 50's > what is the min. & max. powder charge for that combination ?
     
  10. martini

    martini

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    Unfortunately, I don't have any source for non-custom 50 caliber bullets. I'm not aware of any published data for 8208. I would like like to shot 45-50 grain bullets in my 1:10 barrels but bullets in that weight range are not readily available as far as I know.
     
  11. CdnHotshot

    CdnHotshot

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    20BR IMPROVED > 50gr Bergers and IMR8208 which was very promising for accuracy and velocity.
    29.2 grains avg. 3646 fps ES30.0 SD12.00 1.384" group @ 200 yards
    29.5 grains avg. 3670 fps ED21.0 SD 9.00 1.004" group @ 200 yards

    Compared to:
    32.0 RL15 avg. 3658 fps ES35 SD12.0 .835" group @ 200 yards
    33.9 H4350 avg. 3640 fps ES65.0 SD25.0 .982" group @ 200 yards

    IMR8208 ...is the fastest powder of the three and yielded the lowest ES and SD and will be my focus as I move toward choosing a pet load.
    This goes against the thoughts of some who preferred slow burning powders for this calibre.
     
    Last edited: Aug 14, 2018
    Gabe22BR likes this.

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