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25GT Load Data.

Niles Coyote

Niles Coyote

Gunny Sergeant
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    • Aug 13, 2007
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    1,744
    South West, MI
    #1
    For anyone looking at the 25GT, I started using one a couple months back. I got around 500 rounds on it now and a match under its belt (4th place finish at a regional 1 day prs match)

    I haven't seen much in the way of load data so I figured I'd share what I've found so far. I keep this intentionally slow but it should give you an idea of where to start.

    Barrel is a 28" Benchmark chambered by TS Customs with the alpha .180 reamer and installed by me on a Impact 737.

    in the below image I am fire forming new 6mmGT Hornady brass and velocity tends to be about 15-20fps faster after the first firing.

    20240915_222838.jpg


    Bullet being used in the above is a 135 Berger Hybrid jumping around .055", range notes 76 degrees, 67% 29.14 station pressure, little to no wind and time of day was 10 minutes before sunset through 20 minutes after... Limited on time, I had some pretty wicked mirage while shooting H4350 and RL-TS 15.5 coming off my shielded maverick and I know groups were affected but I was really more interested in velocities anyway... by the time I got to the loads with StaBall Match & 6.5 I had so little light left that I stopped for the night.

    Garmin Xero used for velocity collection.

    Top string is Varget
    31.5: 2577, 2570, 2574 = 2574 SD 3.0/7.4 ES
    32.0: 2599, 2602, 2596 = 2599 2.7/6.5
    32.5: 2625, 2625, 2627 = 2626 1.1/2.4
    33.0: 2657, 2649, 2654 = 2653 7.8/3.2

    Middle string H4350, no compression was noted when seating these.
    34.5: 2604, 2595, 2590 = 2596 5.6/13.3
    35.0: 2639, 2642, 2642 = 2641 1.2/2.8
    35.5: 2662, 2664, 2664 = 2663 1.1/2.6
    36.0: 2698, 2685, 2696 = 2693 5.7/13.3

    Bottom String Reloder TS-15.5
    31.5: 2555, 2544, 2543 = 2548 5.3/11.6
    32.0: 2572, 2580, 2578 = 2577 3.6/8.6
    32.5: 2599, 2606, 2603 = 2603 2.7/6.6
    33.0: 2621, 2621, 2629 = 2624 3.8/8.5

    Different day with 135 Bergers Hybrids.
    Vihtavuori N150 31.75gr 16 shots = 2632 SD 6.2/24 ES
    32.75gr 4 shots = 2692 5.7/14.3

    With 134 Hornady ELD seating same jump... .055ish
    Vihtavuori N150 31.75gr 17 shots = 2610 SD 8.9/38.9 ES
     
    Last edited:
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    #2
    a post I made earlier this year...

    Some background on how I got here.
    I've been competing with a 6gt since late 2019.

    Last fall I had a 25x47L spun up for 2024, got the barrel broke in and shot it at two regional matches this past winter.

    Spring rolled around and I realized I had a certificate for a free chamber and fitting job I needed to get turned in quick and I had a spare 6.5 barrel sitting around I had purchased the previous year... long story short I had a 6.5x47L chambered up. I looked at the BC's and bullet weights and figured they would be interesting to compare.

    I am now 700 rounds into the 6.5 shooting A-tip 135's and noticed TS Customs had a barrel sale going in July that I couldn't pass up and a 25 GT found it's way into my home, cause... well... I have 1000 unfired Hornady brass in 6mm GT I got from a buddy named Swanny... way back when I made the switch back in 2019.

    Opened those 6mm necks up for a nice .003" neck tension and started loading them up.

    Barrel is broken in now and I am deciding on what load I want to run for matches now.

    What I can say so far.

    That 6.5x47L is awesome and the sad thing is I already knew that back when I was using one ten years ago. I can say if I were faced with the decision between that and the 25x47L again I'd go to the 6.5 as there are just more bullet options out there and while the 25 version isn't picky by any means... the 6.5 will shoot nearly every load well. That said, this 25 GT is really growing on me. I just like the size. It reminds me of a scaled up 6BR or a scaled down 6.5x47L and it also seems to shoot really well with just about every load I've tried... especially for unfired factory Hornady brass.

    Recoil energy comparison. I set my velocity goal to make the 6.5 and 25 cal match my 109 6GT load at mid range in the wind. I shoot the 109 at around 2830fps, so for the 6.5 and 25 that means mid to low 2600's. I also increased the weight one pound on my 6.5 and 25 cal rifles (21 pounds 1 ounce on each) and recoil energy is now right around half a pound more for each compared to the 6mm. Both give me around a 30% increase in energy on target.

    Can I tell a difference in recoil? Between 25 and 6.5, no. Between 6mm and either of the other two, yes. However, with the extra few hundredths of a second those larger bullets are in the air I feel I "see" the same feedback down range when my bullet arrives, so the little bit more recoil hasn't really been a bother other than getting use to it.

    Going forward, I don't see myself leaving the 6mm but I will also be keeping a 6.5x47 or 25GT for longer range matches.

    search terms: 25 GT 257 .257
     
    Last edited:
    #3
    20241005_134053.jpg


    Next up is 134ELD & N150, again this is all new Hornady brass with the necks opened up with a mandrel for .0025-.003 neck tension. Primers are CCI 450's

    32.0= 2608, 2612, 2612 adv= 2611.4, SD 1.8 / 3.9 ES
    33.0= 2645, 2670, 2666 = 2660.7, 10.9 / 24.9
    34.0= 2711, 2721, 2792 = 2720.8, 7.3 / 17.8
    35.0= 2771, 2794, 2791 = 2785.9, 10.6 / 23.7

    Moving on to StaBALL 6.5 with 135 berger hybrids seated at 1.915' per my SAC comparator which gives me about .055 jump to the lands. New Hornady brass and cci 450 primers

    37.0= 2640,2661,2665 =2655.7 10.9/24.8
    38.0= 2670,2678,2675 =2674.5 3.3/7.9
    39.0= 2736,2734,2735 =2735.4 1.0/2.3

    Same but with StaBALL Match (hang fires on all, just enough to hear the striker impact separate from the muzzle report)

    31.0= 2480,2495,2492 =2489.5 6.3/14.4
    32.0= 2523,2573,2554 =2550.7 20.5/49.8
    33.0= 2609,2649,2629 =2629.3 16.0/39.3

    I had hang fires on my 6mm GT with StaBALL Match as well and figured the temps may have played a roll as it was near zero degree that day, today it was 67 degrees.

    @762 ULTRAMAGA below is a pic of my brass, the three with the 35 grain charge show a very faint ejector swipe. On once fired brass I have been gaining about 20ish fps on other loads so this could put you into that 2800 zone. keep in mind this is a 28" barrel. I do feel that the 25x47L would be a better fit for 2800+ though.

    20241005_131737.jpg
    20241005_131737.jpg
     
    Last edited:
    #4
    Cool thread
    I know you're running them slow intentionally, But.... If you ever feel like experimenting in the name of science I'd love to see where you pressure out with 134s using N150 or Varget.

    I have a 6GT and it's giving me single digit ES with about every load I've used, absolutely a dream to tune.

    I'd like to go with the 25 version for NRL if I can make power factor with it, I know the guaranteed answer is a 25 Creed but I just don't like that case..
     
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    #7
    762 ULTRAMAGA said:
    I'd like to go with the 25 version for NRL if I can make power factor with it, I know the guaranteed answer is a 25 Creed but I just don't like that case..
    Click to expand...
    Any objections to 25x47? I’ve been kicking that idea around for a month, but for PRS

    Should easily get you to 2850 for NRLH
     
    #8
    I've thought about the x47 but nobody has a reamer so I'd be looking at that cost, plus $450 for 300 cases, and another $150 for dies.
    At that point I'd just go 25 Creed since I have match dies and a bunch of Peterson brass..

    Currently I'm thinking long and hard on a 6.5 GT, I could make power factor with 140s at 2720, or 144s at 2640. Pretty damn sure it'd make that, barrel life would be awesome too.

    Sorry OP for the tangent..
     
    #9
    762 ULTRAMAGA said:
    I've thought about the x47 but nobody has a reamer so I'd be looking at that cost, plus $450 for 300 cases, and another $150 for dies.
    At that point I'd just go 25 Creed since I have match dies and a bunch of Peterson brass..

    Currently I'm thinking long and hard on a 6.5 GT, I could make power factor with 140s at 2720, or 144s at 2640. Pretty damn sure it'd make that, barrel life would be awesome too.

    Sorry OP for the tangent..
    Click to expand...
    Since you are referencing power factor, I assume your use case is for NRLH:

    I looked very hard at 25GT and 25x47 for my next NRLH barrel. I have a 25x47 on my open class PRS rig, and with the 28” tube it barely makes PF with a 135 Berger. After considering weight, you won’t want to run a barrel longer than 26” in NRLH, and I don’t think the carbon options are even offered longer than that. Unless you hate reusing brass the GT case will not get you to PF no matter the bullet option (257-6.5 dia.). The smallest cartridges that will reliably (not pushing pressure too hard) make PF are 6.5x47 or 25CM.

    OP - Thanks for the data. It is lacking on this chambering. I do feel that the 25GT is the scaled up Dasher, and expect to see it gain some market share now that the JTAC Crew has been.
     
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    #22
    Niles Coyote said:
    For anyone looking at the 25GT, I started using one a couple months back. I got around 500 rounds on it now and a match under its belt (4th place finish at a regional 1 day prs match)

    I haven't seen much in the way of load data so I figured I'd share what I've found so far. I keep this intentionally slow but it should give you an idea of where to start.

    Barrel is a 28" Benchmark chambered by TS Customs with the alpha .180 reamer and installed by me on a Impact 737.

    in the below image I am fire forming new 6mmGT Hornady brass and velocity tends to be about 15-20fps faster after the first firing.

    View attachment 8502846

    Bullet being used in the above is a 135 Berger Hybrid jumping around .055", range notes 76 degrees, 67% 29.14 station pressure, little to no wind and time of day was 10 minutes before sunset through 20 minutes after... Limited on time, I had some pretty wicked mirage while shooting H4350 and RL-TS 15.5 coming off my shielded maverick and I know groups were affected but I was really more interested in velocities anyway... by the time I got to the loads with StaBall Match & 6.5 I had so little light left that I stopped for the night.

    Garmin Xero used for velocity collection.

    Top string is Varget
    31.5: 2577, 2570, 2574 = 2574 SD 3.0/7.4 ES
    32.0: 2599, 2602, 2596 = 2599 2.7/6.5
    32.5: 2625, 2625, 2627 = 2626 1.1/2.4
    33.0: 2657, 2649, 2654 = 2653 7.8/3.2

    Middle string H4350, no compression was noted when seating these.
    34.5: 2604, 2595, 2590 = 2596 5.6/13.3
    35.0: 2639, 2642, 2642 = 2641 1.2/2.8
    35.5: 2662, 2664, 2664 = 2663 1.1/2.6
    36.0: 2698, 2685, 2696 = 2693 5.7/13.3

    Bottom String Reloder TS-15.5
    31.5: 2555, 2544, 2543 = 2548 5.3/11.6
    32.0: 2572, 2580, 2578 = 2577 3.6/8.6
    32.5: 2599, 2606, 2603 = 2603 2.7/6.6
    33.0: 2621, 2621, 2629 = 2624 3.8/8.5

    Different day with 135 Bergers Hybrids.
    Vihtavuori N150 31.75gr 16 shots = 2632 SD 6.2/24 ES
    32.75gr 4 shots = 2692 5.7/14.3

    With 134 Hornady ELD seating same jump... .055ish
    Vihtavuori N150 31.75gr 17 shots = 2610 SD 8.9/38.9 ES
    Click to expand...
    Varget is just so tough to beat.

    I appreciate that you tried so many different combos. Saves us a lot of time & $ experimenting with powders and projectiles. I'll stay tuned to see your data once you get some larger sample sizes as you dial things in.
     
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    #23
    New Alpha brass is in. Used N150, 135hy at 1.911 and CCI 450'S
    image_cropper_1729195278588.jpg

    31.5 = 2609, 2618, 2638, 2613, 2621, 2633, 2712= 2620 sd10/30es

    31.75= 2599?, 2635, 2651, 2636, 2625 = 2629 17/53... without the odd ball = 2637 9/26

    32.0 = 2656, 2648, 2658, 2644, 2646 = 2651 5/13
     
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