Cbb 120 tmt aa2200
Welcome to the Home of the 6.8 SPC - 68forums.com.
Results 1 to 6 of 6
  1. #1
    6.8 SPC Fan
    Join Date
    Oct 2010
    Location
    Sammamish, WA
    Posts
    399

    Default Cbb 120 tmt aa2200

    I've taken my time on this batch. Once fired S&B brass out of the same rifle. Steel pin washed and polished with corn cob media after bumping neck back 0.003". Brass was sorted by weight and grouped in 5s to the tenth of a gn (didn't switch to g on my scale).

    I worked up loads with HDY 120 SST in preparation for this batch on my ARP 20" Triad Midweight that I built and broke in with S&B 110gr factory ammo. The HDY batch was between 27-28gr of AA2200 @2.295". Found accuracy at the higher end. After reading H's post about pressure testing with the CBB 120 MKT, I figured I would create this ladder for the TMTs at my own risk.

    You can see the recipe on the card. All I need now is some good weather over here on the west side of WA, still winter weather here and it sucks (rain). I'll post up accuracy nodes w/o velocity once I test these.

    IMG_1969.JPG

  2. #2
    68Forums.com Industry Partner
    Join Date
    Jan 2013
    Location
    Last best place
    Posts
    1,731

    Default

    Depending on your rifle of course you should be ok.
    I've run them there.
    Please stop at first signs of pressure and stay safe.
    Cavity Back Bullets

    Home of custom precision CNC milled projectiles and more.

    Affiliates:
    AR15 Performance
    IronWorks Tactical

    The 6.8 SPCII, the best all around cartridge available in the AR15 platform.

  3. #3
    6.8 SPC Fan
    Join Date
    Oct 2010
    Location
    Sammamish, WA
    Posts
    399

    Default

    Thanks. I'll also measure case head expansion on each one once I get to 28. I believe xman has a pretty good article on that to measure over pressure signs (along with the normal ways).

  4. Remove Advertisements
    68Forums.com
    Advertisements
     

  5. #4
    6.8 SPC Lover
    Join Date
    May 2014
    Location
    North FL in the woods
    Posts
    481

    Default

    I'm thinking in the 28's grains of 2200 powder and a 120gr bullet it's going to get interesting, (2) and (3) image.jpg 22" 3-R

  6. #5
    6.8 SPC Fan
    Join Date
    Oct 2010
    Location
    Sammamish, WA
    Posts
    399

    Default Cbb 120 tmt aa2200

    I ran the 5-shot per charge ladder yesterday. Concrete bench, lead sled, hand on scope, pressed trigger until round on target. No pressure signs up to 28.4 gr of AA2200 @ 2.295" OAL in my ARP 20" Triad barrel. I did not see accuracy at the top. 27.5 gr was not enough to reliably cycle the action. I have the gas block set to one click higher than S&B 110gr. Accuracy ranged from 1.5"-3"+ @ 100y. Best charge of the day was 28.0 and 28.1. Will play with OAL from here.

    Last edited by Dogcompany; 05-21-2017 at 01:10 PM.

  7. #6
    68Forums.com lifer
    Join Date
    Jun 2014
    Location
    Stockton, CA
    Posts
    1,008

    Default

    I would take 28.1 and test seating depth longer to get that group to tighten up. I'm still working on fine tuning my long range load with the 120 TMT as well, I'm getting close with it. So far I'm at .75 MOA accuracy and need to get it a fair bit tighter to be acceptable for 600M matches.
    Fear is just excitement in need of an attitude adjustment


 

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •