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6gt

Dthomas3523

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Minuteman
  • Jan 31, 2018
    10,769
    15,792
    South Texas
    There’s a couple threads going on that pop back up from time to time. Now that the cartridge is pretty well understood and all the non load questions are asked, time to make sticky for loads and such.

    My current:

    109 berger 0.020 off
    Cci 450
    34.0 Varget
    Hornady Brass
    2950 fps
     
    109 Berger
    CCI 450
    Hornady brass
    35.5 grs H4350
    2880 FPS

    Even with virgin Hornady brass that I don’t do anything but load or run a mandrel through and load it is shooting great. Great feeding out of my 12 rd unmodified MDT AICS mag in an XLR/Bighorn. Only 1/3 the way through this barrel but besides the speed it’s lived up to the hype for me, I’m happy with it.

    E93C5CF8-B29E-45D5-A453-94E3A4176EBB.jpeg
     
    what barrel life are guys getting now that's it been out a bit?

    My buddy said his took a dump at ~1000-1200rds he was pretty bummed.

    another said he pulled his at 1800. but only because it was a good time to switch to his second GT barrel. he said it was still shooting well
     
    109 Berger
    Alpha brass
    cci 450
    37.0gr H4350
    2900 fps
    24" barrel

    Recently got some of the new Alpha OCD brass and went up to 37.7gr and got 2955 so eventually I will transition to the ocd stuff but my 400 pieces of original Alpha brass are only on the 3rd firing so some good life left in them.
     
    • Like
    Reactions: sandwarrior
    what barrel life are guys getting now that's it been out a bit?

    My buddy said his took a dump at ~1000-1200rds he was pretty bummed.

    another said he pulled his at 1800. but only because it was a good time to switch to his second GT barrel. he said it was still shooting well

    Was his reason for pulling it velocity loss or accuracy? Did he clean it down to the steel and verify?
     
    Was his reason for pulling it velocity loss or accuracy? Did he clean it down to the steel and verify?


    the first guy pulled it cuz velocity dropped and groups opened up. and he couldn't get it back. not sure exactly what he tried. he just told me he has another barrel that's at 1400 and still going strong he just hasn't been shooting it lately.

    the other guy only pulled it because he got another barrel in and didn't want to chance the 1800ct barrel to go on him in a match. he said it had opened up a little bit but was still under 1/2min
     
    the first guy pulled it cuz velocity dropped and groups opened up. and he couldn't get it back. not sure exactly what he tried. he just told me he has another barrel that's at 1400 and still going strong he just hasn't been shooting it lately.

    the other guy only pulled it because he got another barrel in and didn't want to chance the 1800ct barrel to go on him in a match. he said it had opened up a little bit but was still under 1/2min

    I’d be pretty surprised if barrels don’t last at least as long as dasher.

    I stopped running it earlier this year due to the alpha brass fiasco. But running it again now with hornady. I should burn out a couple barrels by mar/april.
     
    @Dthomas3523 are there any issues one needs to know about before jumping into this cartridge? I’ve heard pressure issues but I’m not sure if it’s good info or not.
     
    105 Berger Hybrid .070 off
    CCI 450
    Hornady brass (on 6th firing, pockets still tight)
    34.0 Varget 2,990
    33.5 Varget 2,930
    33.0 RL-16 2,820
    35.8 H4350 2,880
    Stuteville Bartlein 26”MTU prefit.
    How do you like rl16? Are you maxing out at 33gn?
     
    How do you like rl16? Are you maxing out at 33gn?
    I was actually running 33.5 RL16. Typo above. No pressure signs. Found the load from another 6GT thread just to see what it would give me and for data on other powders as back up. Worked great and never bothered trying another charge weight. I dont like to spend too much time chasing SDs and groups. GT has been really easy to load for. Reload it consistent and low SDs by default. I used to run it at 3,020. Now im backing off charge slowly, getting velocities slower and it still shoots. I see no advantage really in running it 3,000 + at PRS matches
     
    Alpha OCD brass
    Fed 205M
    37.0 gr VV N555
    115 Dtacs at -.020
    2775 avg es-17 sd-4.2 for 26 rounds (4 of the 30 round string did not register)
    PXL_20210103_190602692.jpg
    This is w/ 65 rounds on a new Stuteville 26" 7.5 twist. I expect it to speed up to around 2850ish.
     
    what barrel life are guys getting now that's it been out a bit?

    My buddy said his took a dump at ~1000-1200rds he was pretty bummed.

    another said he pulled his at 1800. but only because it was a good time to switch to his second GT barrel. he said it was still shooting well
    I pulled mine at 1950, but it was still shooting well and no velocity loss. I might stick it back on after I get a few more through the new one, and see how far it'll go.
     
    Alpha (non-OCD) and Hornady Brass
    CCI BR4
    H4350 @ 37.75gr
    26" 7.5tw Proof Comp. Contour (GAP Spec chambered by Straight Jacket Armory) - bbl @ ~900rnds
    105Hyb - 3025fps
    108ELDM - 3020fps

    That Hornady Brass is pretty good. Going through it's 4th firing. I do get some cratering and ejector marks, but no heavy bolt lift or extraction issues.
     
    Last edited:
    6mm GT
    BulletPowderChargePrimerBrassCBTOVelocityBBLROT
    6mm GT105Varget33.5450Alpha1.94293230
    6mm GT105Varget34.1450Alpha1.94297930
    6mm GT105Varget34.2205mAlpha301830
    6mm GT105Varget34.5450Alpha1.94300030
    6mm GT105H435037br2Horn3015
    6mm GT105H435037.8205mAlpha1.968301730
    6mm GT105H435037.75BR4Alpha302526
    6mm GT105H435036.5cci 450Horn290026
    6mm GT107N14033.1205mAlpha20 OTL288430
    6mm GT107Varget33.4205mAlpha1.967290830
    6mm GT107Varget34205mAlpha1.967297130
    6mm GT107H435037.8205mAlpha1.967301030
    6mm GT107SW Prec33.8205mAlpha1.967290930
    6mm GT107H435038.2Horn3060
    6mm GT107RL 16Horn3100
    6mm GT108Varget33.2450Alpha1.94289730
    6mm GT108Varget33.5450Alpha1.94296030
    6mm GT108H435036.6205mHorn70 OTL295130
    6mm GT108SW Prec34.1205mHorn1.987298230
    6mm GT109Varget34.5450Horn2950
    6mm GT109Varget65 OTL2910267.5
    6mm GT109Varget34BR4Horn300026
    6mm GT109H435037cci 450alpha290024
    6mm GT110Varget34450Alpha1.9752917
    6mm GT110SW Prec34205mHorn1.983290530
    6mm GT110H435036.9205mHorn38 OTL295030
    6mm GT112Varget33.4br2Horn2915
    6mm GT112Varget33.5450Lapua1.94290030
    6mm GT112Varget33.9450Alpha1.94289030
    6mm GT112H435036.6br2Horn2932
    6mm GT112STA ball39.5br2Horn2965
    6mm GT115Varget32.3450Alpha1.94279430
    6mm GT115Varget33.5450Alpha1.94290130
    6mm GT115Varget34.2450Alpha1.94292430
    6mm GT115RL 1636.9450Horn2855
    6mm GT115RL 1637450Horn2875coated bullet
    6mm GT115H4350Horn2970
    6mm GT115N55536.530 OTL2854267.5
    6mm GT115N55537205mAlpha OCD20 OTL2775267.5low rnd count
     
    Last edited:
    Alpha OCD brass
    Fed 205M
    37.0 gr VV N555
    115 Dtacs at -.020
    2775 avg es-17 sd-4.2 for 26 rounds (4 of the 30 round string did not register)
    View attachment 7526598
    This is w/ 65 rounds on a new Stuteville 26" 7.5 twist. I expect it to speed up to around 2850ish.

    What freebore are you running? I have .120 and 1k DTAC but read they sit deep in the case and cause issues.




    It might be beneficial to post freeborn as well since there are two popular ones out there.

    Standard .120
    Heavy/long .170
     
    Last edited:
    Common 6 GT Powders
    •IMR 4166
    •Varget
    •SW Precision
    •H4350
    •RL16


    From George, Updated 04-03-2020

    AMP Aneal codes. Pilot. 73

    Mk 1 STD mode use code 82

    Aztec mode use 142 for Hornady, 141 for Alpha.

    If you are going to analyze using Aztec use pilot code 073 C

    These are COAL to the lands for various bullets. These were measured on brand new barrels with the OG reamer and the Current, JGS and PTG. there was a +/- variation of .005 either side, so reamers as well as bullets vary lot to lot. They will always vary a tad Chamber to chamber , Rifle to Rifle. . Back off .010 as a MIn.

    103 Vapor Trail 2.560

    105 Berger Hyb 2.585

    105 JLK 2.590

    108 Hornady ELD 2.545

    110 H A Tip. 2.620

    112 Barnes 2.605

    115 Nosler RDF 2.545

    115 DTAC. 2.580

    In looking at these #'s the current .120 FB is still the best for the standard Reamer as it will work well for everything and is the best for 105-109 Berger Hybrids, 112 Barnes and the Hornady 110 Atip

    If guys were wanting a specific chamber cut for 115 RDF, 115 Sierra, 108 Hornady ELD or 103 Vapor Trail a .170 FB would probably be ideal for those 3 bullets which GAP does have a .170 FB Reamer but Its only used on request.
     
    26” PVA Zermatt Origin
    Virgin Hornady brass
    109 Berger .040 jump
    34.3gr Varget 2900 fps
    Winchester primer
    SD 2

    I get some cratering, but nothing crazy. I have some CCI 400s I can try as well.

    Break-in load
    Hornady brass
    33.5gr Varget
    Hornady 108 ELD .020” jump
    Winchester primer
    No velocity data
     
    Berger 109
    37.6 H4350
    0.020 jump
    CCI 450
    Alpha Brass
    3000 fps from Hawk Hill 26" bbl

    Berger 109
    34.5 Varget
    0.020 jump
    CCI 450
    Alpha OCD Brass
    2921 fps from Stuteville/Bartlein 26" bbl (brand new, expect more speed)

    Both are single digit ES and SD among continuous 10 shot groups.
     
    • Like
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    I wish they would replace my standard brass with the OCD stuff but it isn’t that big of a deal really. I just don’t load them extremely fast. Running a 108 with H4350 at 2980 without any issue.
     
    You'd think alpha would make things right with their customers. I thought their Creedmoor cases were soft too so sold em. Maybe all alpha brass is soft? They had to OCD to get it to hold same psi as lapua/Peterson, hopefully they spread that through all their cases and it becomes standard.

    Anytime I complained, I was told by alpha and their supporters it was my fault or the barrel had a tight bore (3 bartleins and 1 proof).

    So......🤷‍♂️🤷‍♂️🤷‍♂️
     
    What freebore are you running? I have .120 and 1k DTAC but read they sit deep in the case and cause issues.




    It might be beneficial to post freeborn as well since there are two popular ones out there.

    Standard .120
    Heavy/long .170
    I didn't add the freebore, because I have no idea what it is. It's whatever reamer Stuteville uses.
    Honestly, I don't really care. I start at -.020 and as long as the bullet/powder combo is under 3/4" at 100, and ES is under 30 (at least 20 rds.) I'm off and running.
     
    what barrel life are guys getting now that's it been out a bit?

    My buddy said his took a dump at ~1000-1200rds he was pretty bummed.

    another said he pulled his at 1800. but only because it was a good time to switch to his second GT barrel. he said it was still shooting well

    I’m just under 3k and mine is still going strong so not sure what’s wrong with his.
     
    Hornady 110 A-Tips
    .30 off
    Hornady brass
    CCI 450’s
    34.5 varget 2950

    Berger 109 Hybrids
    .60 off
    Hornady brass
    CCI 450’s
    34.5 Varget
    2950

    Berger 109 Hybrids
    .60 off
    Hornady brass
    CCI 450’s
    Varget 33.2
    2870

    Berger 105 Hyrbids
    .60 off
    Hornady brass
    CCI 450’s
    Varget 34.5
    3050

    Berger 105 Hybrids
    .60 off
    Hornady brass
    Varget 33.8
    2950
     
    I wish they would replace my standard brass with the OCD stuff but it isn’t that big of a deal really. I just don’t load them extremely fast. Running a 108 with H4350 at 2980 without any issue.


    They did make some newer 6GT brass that was the OCD. So far all the reports I’ve seen of people using it had no issues. Not like the original.

    I’m waiting for more to come back in stock. Will probably switch to that from the Hornady. The Hornady has worked fine but after about 7 firings on it many of the pockets are starting to loosen on mine.
     
    A friend and I both got Gaprecision production class 6gt rifles a week ago. At 2499 they are a great deal I am using new hornady brass and dies with 100 of both 105s and 109s Bergers
    winchester small primer
    34grs Vit 140
    2.590 OAL So far the 105s OAL is way more consistent than 109s with Hornady dies and smaller group at 300yds ,I am going to do more testing at 300. need to buy more bullets I can find 109s but no 105s. Whats others experience with 109s and 105s thanks
     
    For those full length sizing with bushing dies and Hornady brass - Any recommendations on bushing sizes?

    GAP is recommending starting with 0.266" which seems small to me based on what has worked for 6.5 creedmoor Hornady brass. I am measuring (caliper) the neck wall thicknesses 0.015" on new 6GT brass and trying to achieve 0.002" neck tension. Planning to use 21 century turning mandel in an expander die.
     
    For those full length sizing with bushing dies and Hornady brass - Any recommendations on bushing sizes?

    GAP is recommending starting with 0.266" which seems small to me based on what has worked for 6.5 creedmoor Hornady brass. I am measuring (caliper) the neck wall thicknesses 0.015" on new 6GT brass and trying to achieve 0.002" neck tension. Planning to use 21 century turning mandel in an expander die.

    Get a micrometer. I highly doubt it’s .015 neck.

    If it is, you might want to look into turning the necks. You’ll be at .273 loaded on a .274 chamber.
     
    • Like
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    For those full length sizing with bushing dies and Hornady brass - Any recommendations on bushing sizes?

    GAP is recommending starting with 0.266" which seems small to me based on what has worked for 6.5 creedmoor Hornady brass. I am measuring (caliper) the neck wall thicknesses 0.015" on new 6GT brass and trying to achieve 0.002" neck tension. Planning to use 21 century turning mandel in an expander die.
    I use a 266 bushing.
     
    • Like
    Reactions: TreyMeTrey
    Get a micrometer. I highly doubt it’s .015 neck.

    If it is, you might want to look into turning the necks. You’ll be at .273 loaded on a .274 chamber.
    I use a 266 bushing.

    Thank you. You're right, measurement was off and I do need to get a micrometer. Re-measured with some bias and it is probably closer to .0135-.014. The .266 bushing makes sense.
     
    • Like
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    Sure looks like the 109gr Hybrid likes the nodes at 2880 and 2950fps.

    I guess a guy has to decide between chasing that higher node or running low and slow like some of the top shooters are trending..
     
    • Like
    Reactions: Darkside-Six
    Did George spec a new neck diameter? The print he posted online is 273. I hope he changed it, it was too tight to alpha brass in my opinion.

    I think I misremembered. I thought it was a .274 and everything I have says .273.

    I think they were trying to give everyone a place. Guys that neck turn wouldn’t have a ton of clearance, and guys that don’t would still have enough.

    IMO, any 6mm reamer made for no neck turning should be .275
     
    The 6GT was the easiest to load develop I have personally ever seen. Running 34.4-35 of Varget has 8 FPS total speed difference with the 105 Berger. I settled on 34.5 Varget, Hornady brass, FGMM primers and honestly just picked a number for COAL to seat the bullets and never checked the jump. It shot single digit SDs and tiny .25” groups at 2954. I decided I would try a 109 with the same load and it was almost identical results but being slightly slower. I am running a 26” A-Team precision profile Mullerworks barrel (Impact prefit)spun up by BrIan Allen. I went ahead and ordered another barrel I was so well pleased with it.
     
    Sure looks like the 109gr Hybrid likes the nodes at 2880 and 2950fps.

    I guess a guy has to decide between chasing that higher node or running low and slow like some of the top shooters are trending..
    I personally went with the slower one. Mine is 2870 but less recoil and can see trace better. Plus not as hard on the barrel.