My first tests for 125 gr Partition (long post)

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  • grayfox
    Chieftain
    • Jan 2017
    • 4295

    My first tests for 125 gr Partition (long post)

    I've attached the first results of my tryout of the 125 gr Nosler partition bullet.
    The range is indoor, 100 yds, about 75 deg F.
    I used CFE223 powder,
    cci450's,
    1x fired hornady brass,
    Nosler 125 gr Partitions,
    seated to 2.252-2.255, which is less than the lands in my rifle
    (2.263-2.265 was my measurement for this bullet to lands).
    Not that this is the optimum depth, I was trying to ensure I didn't engage the lands yet give as much room as possible for the powder.

    I didn't recall until at the range that I had re-adjusted the scope on this rifle slightly so I needed to do some re-zeroing. This I did, with my magnetospeed attached, and using some Vmax-95 loads (30.1 xbr), an accurate and medium-type load for me.

    I had loaded 2 each of a ladder of CFE charges, 1 each shot as a speed indicator, then take the magnetospeed off and shoot the remaining 1 each as a ladder to see how they track on paper.
    The speed readings I obtained were as follows (I also put them on the sheet next to the shots from the 2d, non-magneto-ladder):
    1. 29.3 gr: 2396 ft/sec
    2. 29.6 gr: 2420
    3. 29.9 gr: 2433
    4. 30.2 gr: 2458
    5. 30.5 gr: 2485
    6. 30.8 gr: 2497
    7. 31.0 gr: 2531

    After the speed tests, I removed the chrono and re-zeroed, using some more 95 vmaxes. I just wanted to be close to the black dots so the results might look intelligible. (My experience with my MG-speed shows it does cause a POI shift.)

    As far as I could tell most of the ejects went 2:00-3:00, either bouncing off of my bag (at 2:00) or straight out to the cube wall at the range. My guess is they are somewhat overgassed but then again everything I've loaded so far has been that way. (The only major fail this trip was my Caldwell brass catcher wouldn't install - I had put the bag's rail attachment onto the rail in the wrong spot - o well, try to watch ejections as they occur...)

    Primers do not appear to be flat, or might be just a tad but I haven't punched them out yet. Brass looked normal, much like any other ejects I've done.

    The attached pic shows the second round of shots along with speeds from the first round.
    I can't draw a lot of conclusions from these results but I think I succeeded in a couple of points:
    1. Use of CFE with the 125 partition is definitely a useable powder for my Grendel.
    2. Bullet velocities can approach 2500+/- in this rifle (2505 is a node for this one).
    3. 31.0 gr might be the start of too hot, b/c the sudden jump (2497-2531, 35 ft/s) is bigger than any other, anyway I sort of expected it to be around 31.0 for me.

    As a final step I did a 3-shot of some 123 sst hand-loads I have that closely approach the Hornady factory loads for this gun. The lower one I pulled a bit and again the upper I know I flinched some, but overall it still is ~ 1 moa, even better on some days... So this "x" gives an approximate location as a reference for the session too.

    Anyway that's my report for this session.
    Attached Files
    "Down the floor, out the door, Go Brandon Go!!!!!"
  • LRRPF52
    Super Moderator
    • Sep 2014
    • 8569

    #2
    Nice report. CFE223 is one of the ideal powders for the 125gr Partition.

    Judging from your trend line, if it's repeatable, 30.9gr is probably your cut-off.

    What barrel length are you shooting?

    Once you settle on a load, you should have pretty tight accuracy because they are more like a flat base. I have doubts about their published BC of .449, since there really isn't much of a boat tail to speak of, but still a good 325yd hunting bullet when mv is 2500fps. I suspect the BC is more like .400-.410 G1, and G1 drag model is ideal for this bullet since it will be shot within 600yds for sure.

    In testing for Volume II, the 100gr Partition expanded down to 1847fps, with frontal core separation. The nose is skived so that the jacket peels open symmetrically, for a spinning razor pedal effect through the tissue, with nice expansion from the frontal core, without loss of the rear core due to the partition wall of the projectile jacket. This used to be the gold standard in a lot of people's minds for what a good hunting bullet was, since the popularity of magnum cartridges took hold in the US and pushed projectiles past their limits with regard to construction. It was really meant for faster cartridges that stress the limitations of cup and core bullet technology before the bonding process was applied to bullets like the Nosler Accubond and Hornady Interbond.

    From the Nosler premium line, I really like the 129gr ABLR, which I feel is a good replacement for the 130gr Accubond, especially in 6.5 Grendel. Since the 129gr ABLR is designed to expand down to 1300fps, and has a verified G1 BC of .553, G7 of .283, it retains energy extremely well, and is ideal for even Grendel SBR speeds.

    Once you settle on some load ranges and produce small sample runs of them, you should have some ragged hole targets with the 125gr Partition. Looking forward to how it turns out for you.
    NRA Basic, Pistol, Rifle, Shotgun, RSO

    CCW, CQM, DM, Long Range Rifle Instructor

    6.5 Grendel Reloading Handbooks & chamber brushes can be found here:

    www.AR15buildbox.com

    Comment

    • grayfox
      Chieftain
      • Jan 2017
      • 4295

      #3
      Originally posted by LRRPF52 View Post
      Nice report. CFE223 is one of the ideal powders for the 125gr Partition.

      Judging from your trend line, if it's repeatable, 30.9gr is probably your cut-off.

      What barrel length are you shooting?

      Once you settle on a load, you should have pretty tight accuracy because they are more like a flat base. I have doubts about their published BC of .449, since there really isn't much of a boat tail to speak of, but still a good 325yd hunting bullet when mv is 2500fps. I suspect the BC is more like .400-.410 G1, and G1 drag model is ideal for this bullet since it will be shot within 600yds for sure.

      In testing for Volume II, the 100gr Partition expanded down to 1847fps, with frontal core separation. The nose is skived so that the jacket peels open symmetrically, for a spinning razor pedal effect through the tissue, with nice expansion from the frontal core, without loss of the rear core due to the partition wall of the projectile jacket. This used to be the gold standard in a lot of people's minds for what a good hunting bullet was, since the popularity of magnum cartridges took hold in the US and pushed projectiles past their limits with regard to construction. It was really meant for faster cartridges that stress the limitations of cup and core bullet technology before the bonding process was applied to bullets like the Nosler Accubond and Hornady Interbond.

      From the Nosler premium line, I really like the 129gr ABLR, which I feel is a good replacement for the 130gr Accubond, especially in 6.5 Grendel. Since the 129gr ABLR is designed to expand down to 1300fps, and has a verified G1 BC of .553, G7 of .283, it retains energy extremely well, and is ideal for even Grendel SBR speeds.

      Once you settle on some load ranges and produce small sample runs of them, you should have some ragged hole targets with the 125gr Partition. Looking forward to how it turns out for you.
      18" barrel. I have some 130's, was a little concerned if the length of the 129 would be too long.
      I might have to give them a try.
      I'm pretty pleased with these initial results. Further development to come.
      I'm sure those "ragged holes" are out there but some of that will depend on the amateur pulling the trigger.....
      "Down the floor, out the door, Go Brandon Go!!!!!"

      Comment

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