6GT project/range report

Discussion in '6mm, 6.5mm, and .25 Cal (Not 6BR)' started by NorCalVu, May 24, 2019.

  1. NorCalVu

    NorCalVu

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    As a lot of you have already heard and seen, George Gardner of GA Precision and Tom Jacobs (2x 600yd/1000yd Benchrest Shooter of the Year) have developed a new round called the 6GT.

    Some basic info on the 6GT:

    Brass can be formed from: 6.5x47L

    35 degree shoulder for better feeding.

    No magazine inserts or modifications required.

    Optimal case efficiency @ 34-35.5 grains of varget.

    3020-3080 fps with 103-105 grain bullets and approx 3000 fps with 115's.

    Alpha will be coming out with commercial brass by August of 2019.

    Dies are currently available from Hornady. RCBS and Redding are due by late fall of 2019

    Reamers and Head space gauges are available through GA Precision.

    I was just about to pull the trigger on a Dasher build but the 6GT popped up. After doing some reading and talking to George I decided to get one spun up to gather real world data vs. the Dasher, 6BRA, 6BR, 6BRX, and 6CMs we have in our club.

    My wants:

    1. Push a 115gn DTAC @ 2920 to 2930fps safely in the Sacramento heat.

    2. Commercial brass (soon) I don't mind forming to get the ball rolling, but don't want to make 1000s of pieces from scratch.

    3. No freaking mag kits. I want to run the same mag I do with every other caliber I own. 260rem, 6.5x47L, 308win, ect.

    4. Barrel needs to go 2200 to 2500 rounds with match grade reliability and accuracy. Subjective and will vary by individual needs. Luckily I don't shoot very tight.

    George said the 6GT will do everything I am looking for so here we are.

    Rifle specs:

    GAP Templar Action

    Bartlein 1:7.7 twist 6mm M40 Contour finished @ 26"

    Huber Trigger Single Stage

    KMW Sentinel Stock

    Vortex Optics 4-27 Razor

    APA Lil Bastard Brake

    He was also kind enough to send me 20 loaded rounds made from 6.5x47 brass, some Alpha brass to test, dies, Giraud shell holder, and answer a bunch of text concerning forming brass.

    I have not done a lot of wildcat type rounds so I enlisted Dan Bertocchini's aka "Dasher Dan" help. He likes to geek out on this stuff and has a lot more experience than I do with this type of thing. Dan also shoots a lot tighter than I do.

    [​IMG]

    [​IMG]

    The 6GT was formed initially from 6.5x47L. The size of the cartridge is between a Dasher and 6x47L.

    Left to Right
    Dasher - 6GT - 6x47L
    Water Capacity of the 6GT made from 6.5x47 is 43.3gn
    [​IMG]
     
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  2. NorCalVu

    NorCalVu

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    Making 6GT Brass

    I have not done a lot of "wildcating" so I enlisted Dan Bertocchini's aka "Dasher Dan" help. He likes to geek out on this stuff and has a lot more experience than I do. Dan also shoots a lot tighter groups than I do, so that'll help with range reports.

    If you like reloading AND have all the tools, it's actually not bad to do. If you hate to be in the reloading room but have the desire to try the 6GT, wait till Alpha comes out with brass.

    Setup did take a bit but the process should go a lot faster now that we are dialed in.

    Tools needed:
    Hornady 6GT dies.
    Giraud Trimmer
    Giraud Annealer

    Neck turner with 35 degree cutter and 6mm setup. I have the 21st Century power lathe turner which made this process a lot easier and faster. Turning the necks is the longest part of the process.

    Mini Chop Saw from Harbor Freight (30.00). No, I am not joking and yes, you need a lil chop saw. Think 300blk out days before brass was readily available.
    2 presses is a huge help.

    Steps 1-5 will get you 6GT brass that will chamber and shoot, but have a quite a bit of run out and I don't think it's optimum for load dev.

    Step 1: FL all your 6.5x47L brass if it has been fired.
    Step 2: Run it through the 6GT sizer with a .266 bushing. You will need to run the case up a little at a time. George told me to size the neck, then 100thou each push of the ram, back off each time.
    Step 3: Chop the long neck off so you only have to trim a little bit with the Giraud.
    Step 4: Trim on Giraud: Length:
    Step 4: Turn the necks. You will have a bit of brass to remove as there is a huge donut from pushing all that brass down.
    Step 5: Tumble and load.

    Note: I would anneal after the first firing for sure.

    I took a few extra steps to ensure I had as nice as factory brass as possible for load dev.

    Instead of Step 5: Tumble and load, I decided to form the cases using the cream of wheat method of forming. (COW) This is the first time I have ever done this and it actually works pretty well. I was able to form 175 cases in about 1.5 hours without burning up the barrel or components.

    Using two old RCBS manual powder drops, I was able to charge cases quickly.
    [​IMG]

    Step 6: Drop 8.0gn of Hodgon Titegroup and fill the case up with COW to the necks. Stuff a piece of tissue in it so the COW and powder stays put. I will also add that use regular small rifle primers as well. No need for CCI 450s for this process.

    Step 7: Fire the COW loaded rounds. If you have never done this, it's loud. Sounds like a pistol going off. Ear pro still a must.

    Step 8: Tumble and anneal.

    Step 8: Resize with 6GT dies.

    Step 9: (you can skip this but I am OCD), I threw the cases back on the neck turner to hit any high spots. It took a lil off.

    Step 9: Resize and load. At this point you have as perfect a piece of brass that can be. I am hoping to match the quality of factory Alpha brass when it comes out.

    The piece of brass on the left is how the case looks after COW fire forming.
    [​IMG]

    Below is a pic of what the brass looks like going through the process.
    Left to right: 6.5x47L brass, sized with the 6GT bushing die with a .266 bushing, chopped/trimmed and turned, and fired formed.
    [​IMG]

    Chop saw action![​IMG]

    21st Century Powered Neck Turning Lathe is the cat's meow of neck turners.
    [​IMG]

    Ready to load:
    [​IMG]

    First 6GT round:
    [​IMG]

    I made an OAL case gauge from a fire formed case:
    [​IMG]

    This is what I got for each bullet measured with Ogive touching the lands:

    105gn Berger Hybrid: 1.950"
    108gn Hornady ELDM: 1.960"
    110gn Hornady ATip: 1.980"
    112gn Barnes Match Burner: 1.970"
    115gn DTAC: 1.960"
     
    Last edited: May 24, 2019
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  3. NorCalVu

    NorCalVu

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    First time on the range!

    May 11th
    Dan took the gun out for initial break in. All rounds were fired at 200yards at Sac Valley Shooting Center.

    We were able to load 49 rounds in our first session. I have no idea how we did not end up with 50......

    3 rounds were shot @ GAP for pressure testing.
    20 rounds of GAP loaded 105 Hybrids were fired.
    49 rounds of forming and test loads were fired.

    First 10 rounds out of the gun:
    GAP Loaded 105 Hybrids. I think Dan said the velocity was 2975fps?
    [​IMG]

    Next 5 of the GAP 105 Hybrid Ammo
    [​IMG]

    Non-Formed Brass
    105gn Hybrid
    34.5gn of Varget - 3020fps
    [​IMG]

    Non-Formed Brass
    105gn Hybrid
    33.5gn of Varget
    [​IMG]

    Non-Formed Brass
    108 ELDM
    33.5gn Varget 2960
    Dan called the one at 11oclocked. Noob.
    [​IMG]

    The 115s did not shoot as well. I think we loaded them way too long because they were a PITA to chamber. That being said, 33.5 got 2915FPS on a new barrel.

    Dan wanted to try some speed test with H4350 and 115s, so we did.

    36.5gn only got 2888FPS.





     
    Last edited: May 24, 2019
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  4. NorCalVu

    NorCalVu

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    Round Count Log:

    3 rounds were shot @ GAP for pressure testing.
    20 rounds of GAP loaded 105 Hybrids were fired.
    49 rounds of forming and test loads were fired.

    Cream of wheat fire formed 175 cases with 8.0gn of Tite Group.

    87 rounds 5-27-19 load dev
     
    Last edited: May 28, 2019
  5. NorCalVu

    NorCalVu

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    Notes:

    Small flash hole on x47 brass will not work with Hornady 6GT die set, which is made for large flash holes.
    Resolution: Ran the depriming pin out long on the x47 die and de-primed the 6GT brass, then sized.

     
    Last edited: May 24, 2019
  6. NorCalVu

    NorCalVu

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    5-27-19 Load Dev Range Report

    Cleaned the barrel so I fouled it in with 5 rounds using brand new Alpha brass. These were the first 5 out of the barrel that AM. Moved the zero a touch, fired 3 more.
    [​IMG]
    Checked Zero @ 200yds to foul the barrel in a little. This was with Cream of wheat (COW) formed brass.
    [​IMG]
    Ran these bullets: 105 Berger Hybrids, 108 Hornady ELDM, 110 Hornady ATip, 112 Barnes Match Burner, and 115 DTAC

    Data gathered. Looks like I got a solid load for 105s, 108s, 110s, and 112s. Gotta work on that 115s. Dan did most of the shooting while I wrote down numbers and worked the Magnetospeed.

    Fired 12 rounds and then let the barrel cool down each time. Will probably load up the 108s and run them out to distance this weekend at our LR match.

    [​IMG]

    Fired 4 rounds of each, except for Target # 15
    [​IMG]

    [​IMG]
     
    Last edited: May 28, 2019
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  7. NorCalVu

    NorCalVu

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    5-31-19 Shot a NCPPRC LR Practice from 200, 300, 425, 500, 600, 800, 900, and 1000.

    Used the COW formed brass (still has a fair amount of run out), but was able to gather pretty solid numbers all the way out.

    Used the 108ELDM pushed by 33.5gn of Varget giving me about 2940. Barrel is broke in and sped up.

    Conditions were nice. Got into the mid 80s by 11am. Winds were from 11 to 2oclock.

    10ring is 4"x3"

    Kestrel and everything tracked pretty well. 10ring is 4"x3"

    [​IMG]

    Shot the match on Saturday and Sunday. Saturday went OK, blew some wind calls at distance that cost me. The .270BC life is something I am not use to coming from a 6.5mm 140gn bullet.

    Here are some groups from that match. We shoot 3 round per string at various distances.

    [​IMG]

    [​IMG]

    [​IMG]


    [​IMG]

    Dropped 1 out of 12 @ 900. Pretty decent water line considering the mirage and me just not being the worlds best shooter. LOL Brass was COW formed. Should tighten up a lil with full formed brass.

    [​IMG]
     
    Last edited: Jun 4, 2019
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  8. NorCalVu

    NorCalVu

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    Range reports
     
  9. Forum Boss

    Forum Boss Administrator

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    Vu -- Thanks for the outstanding report. Some pretty smart guys say this little GT has lots of potential -- for many different disciplines -- Benchrest, PRS, Silhouette, varmint hunting and more.

    Thanks for showing how the 6.5x47 Lapua case is shortened, then trimmed. That chop saw looks efficient! And yes, the 21st Century powered Neck-turning lathe is a great tool that achieves superb results fast!
     
    Last edited: May 24, 2019
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  10. dstoenner

    dstoenner Silver $$ Contributor

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    I think this thread just got the Good Housekeeping stamp of approval

    And i also agree great thread with lots of good data. FWIW I shoot the 6x47L also and for my practice brass to keep cost down i form them from 6 or 6.5 Creedmoor brass from range pickup. Like yours it takes a lot of steps but i am retired. I get about 85% perfect cases out of Creedmoor where when i first tried 260 brass i was only getting about 50% or less. Problem is pushing the shoulder back a long distance causes a lot of cases to fold in on the shoulder.

    David
     
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  11. swd

    swd Gold $$ Contributor

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    Vu do yourself a favor and try some RL16 in that bad boy. It’s wonderful in the Dasher and BRX and seems like it would be perfect in the GT. More speed and less pressure.

    I’ll be at range 12 tomorrow shooting F and can spare a little if want to come up.
     
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  12. NorCalVu

    NorCalVu

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    I won't be able to sneak to the range until Monday. Got almost 80 rounds loaded up with various bullets and loads, all with varget though. Appreciate the offer!

    Once I have a solid Varget load (since this case was designed around it), I will gladly try other powders. H4895 has my attention as a lot of the BRA guys are running it.

    I should have more data after Monday.

    Vu
     
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  13. Willow

    Willow

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    I'd look closely at RL15
     
  14. boltfluter

    boltfluter Gold $$ Contributor

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    Looks like a cool little round! Wondering what this will do that 6XC won't do? The bench rest guys should have lots of fun with this little case. Should feed great as well for PRS . Looking forward to more results with this neat looking round. Carry on! :D:D

    Paul
     
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  15. Stubb

    Stubb Silver $$ Contributor

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    Vu,
    I have a Smith turning a barrel for me as we speak. Where did you find the dies? I have been unable to locate any.

    David
     
  16. Dave Marshall

    Dave Marshall

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    I would advise anyone thinking of going with this cartridge to think twice. Choosing a cartridge with Alpha Munitions as the only brass maker might leave you disappointed or worse.

    I bought some of their 6xc SRP last year with disastrous results. Not one single piece of Alpha brass that I fired performed as new brass should. All of the cases were very difficult to extract after being fired with a very mild load. Two pieces actually ruptured at the base blasting my face with bits of metal and destroying two bottom metal assemblies. When I switched back to Norma and Petersen brass in the same rifle, barrel, load, and chamber, all of the issues that the Alpha brass displayed disappeared.

    In the end I was left with twice the cost of the original brass order in repair costs, and a new respect for safety glasses.
     

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  17. NorCalVu

    NorCalVu

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    David, hit up George Gardner at GAP. If you can wait. I am a RCBS and Redding guy so if you are not in a hurry, wait till those come out.
     
  18. Ledd Slinger

    Ledd Slinger Gold $$ Contributor

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    Cool round but every nook and cranny has already been filled in the 6mm lineup so not sure what any benefits there are for another round in the pile. Guess it's just something different.
     
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  19. rockrat

    rockrat

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    Might work perfectly for our Varmint Silhouette matches here
     
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  20. NorCalVu

    NorCalVu

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    Dave,

    First report of this type of thing I have seen reporting with Alpha.

    Curious, what did they say when you contacted them about the issue? Was the root cause ever discovered?

    If the GT is a performer, I think other brass makers will jump on board. That being said, I am here to report what I find about the GT. When I get my hands on some production GT brass, I'll report on the performance of the brass as well.
     
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