6gt
- Thread starter Dthomas3523
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Wife's 6gt. 37.1 N555. 109 Berger .040 off. I'll take it. Running this at distance tomorrow.
I had an interesting experience with Hornady 6GT brass last weekend. My "go to" load is a Hornady 109 ELDM over 34.0 grains Varget. My SD for Alpha brass was 5.2. SD with Hornady brass was 17.5. I did not expect to such a dramatic difference in SD. I'm throwing out the Hornady brass as it's shot.
109’s jumping 50 around 2930 fps just works, three shot groups at 600 yds, different powder charge s
6GT .120 fb, .272 nk
28" Mueller, .236 bore
37.2 gr H4350, Alpha, 205m, 267 bush
109 Berger 50 OTL
2939 fps avg
6GT .120 fb, .272 nk
28" Mueller, .236 bore
37.2 gr H4350, Alpha, 205m, 267 bush
109 Berger 50 OTL
2939 fps avg
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Yes. It shot good, but the 115 dtacs shot better. Less vertical and held in wind better.
John - what do you suggest for powder charge behind the DTAC? Thanks very much. ELN
Yeah. I have 3 loads for this rig, all with 115 DTAC. N160 @ 2836, N555 @ 2891 and N555 @ 2820. They are all fantastic loads. @WyomingShooter - The thing to consider is recoil management. No issues somewhere around 600 yards with faster loads. However, inside 600 it can be difficult to see trace and impacts. I have shot everyone of these to 2130 without any issues. Recoil impulse is much more forgiving at 2820. If you are not on a clock, making positional changes, etc, the higher load works. Doing the math you only lose approximately .1 in a 10 mph wind at 1k. If you want to buck more wind you need to get the 115 over 3k fps. Slow works for me. I know how to read wind and mirage. Ymmv.
Edited for the correct speeds - I originally posted for my 25x47 - it was late. I can run the 115s over 2900, but recoil impulse sucks there, they run better slower, 2820 is a good place for the DTAC.
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This isn't critique, Mr. Glidewell, just thinking out loud. If you're running 25GT with 135s in the low 2700-fps neighborhood, 6GT with 109s at 2850 should be a pussy cat to handle (I run 25x47 135s at 2735, and 6GT 109s at 2835). I imagine the 6 is even easier at 2720, but you're already at an "energy on target" deficit there, and at low to mid 2800s, it's still less recoil energy than the 25 at 2700 
FWIW, Varget and N150 yield the same velocity for me at the same charge weight in 6GT - currently running 33.5 of Varget in a 26" tube to get 2835 with a Berger 109. All it shoots is boring little one hole groups. I previously ran H4350. Haven't tried either N140 or N160, personally.
FWIW, Varget and N150 yield the same velocity for me at the same charge weight in 6GT - currently running 33.5 of Varget in a 26" tube to get 2835 with a Berger 109. All it shoots is boring little one hole groups. I previously ran H4350. Haven't tried either N140 or N160, personally.
I corrected it, lol. It was late. I was thinking 25x47 for some reason.This isn't critique, Mr. Glidewell, just thinking out loud. If you're running 25GT with 135s in the low 2700-fps neighborhood, 6GT with 109s at 2850 should be a pussy cat to handle (I run 25x47 135s at 2735, and 6GT 109s at 2835). I imagine the 6 is even easier at 2720, but you're already at an "energy on target" deficit there, and at low to mid 2800s, it's still less recoil energy than the 25 at 2700
FWIW, Varget and N150 yield the same velocity for me at the same charge weight in 6GT - currently running 33.5 of Varget in a 26" tube to get 2835 with a Berger 109. All it shoots is boring little one hole groups. I previously ran H4350. Haven't tried either N140 or N160, personally.
This isn't critique, Mr. Glidewell, just thinking out loud. If you're running 25GT with 135s in the low 2700-fps neighborhood, 6GT with 109s at 2850 should be a pussy cat to handle (I run 25x47 135s at 2735, and 6GT 109s at 2835). I imagine the 6 is even easier at 2720, but you're already at an "energy on target" deficit there, and at low to mid 2800s, it's still less recoil energy than the 25 at 2700
FWIW, Varget and N150 yield the same velocity for me at the same charge weight in 6GT - currently running 33.5 of Varget in a 26" tube to get 2835 with a Berger 109. All it shoots is boring little one hole groups. I previously ran H4350. Haven't tried either N140 or N160, personally.
I would suggest not wasting time with N140....I shoot a GT and a BRA and N140 is to fast in the BRA so 99% sure it will not work well in the GT.
I'm about to switch back to running DTACs at ~2800fps with ~33-34gn of Varget when I spin on a new barrel in the next couple hundred rounds or so...
I've been shooting 106 A-tips at 2805fps with 33gn of SWPR for the better part of the last year over the life of my current barrel (I tried running ~2850 and ~2900fps, but liked it better slower at ~2800, the extra speed didn't give me anything besides more recoil), and while it's been good... there's something fucking great about the heavier DTACs that's just Goldilocks IMHO as far as having both soft recoil and downrange performance, and for my brain/eyes ~2800fps is where I wanna be for seeing plates move inside 500 yards.
~10 grains of extra mass doesn't seem like it should matter so much, but it does. I think throwing a bigger rock, slower, works better for me.
I kind of wish someone would make some even heavier pills, like maybe a 120 or 125 for 6mm, just to try, who knows..?
I've been shooting 106 A-tips at 2805fps with 33gn of SWPR for the better part of the last year over the life of my current barrel (I tried running ~2850 and ~2900fps, but liked it better slower at ~2800, the extra speed didn't give me anything besides more recoil), and while it's been good... there's something fucking great about the heavier DTACs that's just Goldilocks IMHO as far as having both soft recoil and downrange performance, and for my brain/eyes ~2800fps is where I wanna be for seeing plates move inside 500 yards.
~10 grains of extra mass doesn't seem like it should matter so much, but it does. I think throwing a bigger rock, slower, works better for me.
I kind of wish someone would make some even heavier pills, like maybe a 120 or 125 for 6mm, just to try, who knows..?
just go 25gt. 135s have great BC and you can run them at 2700 in the GT case.
As soon as when/if we can go the easy route and just order ~$500ish .25cal Proof prefits 2 or 3 at a time like I’ve been doing for the last few years, I’ll see ya in the .25cal section lol. I’m too spoiled, cheap, or both to order custom barrels like a lot of you guys lol.
(In fact, I’ve got to remember to email Proof and inquire if that’s on the horizon?)
ETA: shit, I guess .25CM is already available… the new prices are ouch though, list/MSRP used to be $575
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I had some nice groups with my light 6GT yesterday. I screwed this one together from an Impact Action, Carbon 6 barrel, and Stocky's carbon VFG stock.
Gents,
Got my GT put together finally and took it to the range. Ran into some pressure issues that I’m thinking is brass related. Any insight would be appreciated as this is my first GT.
Rifle:
Tikka action with PVA m24 prefit at 21”
Alpha NON-OCD cases virgin
109 eldms @ 2.580 COAL .040 off the lands
32.5-34 grains of Varget
Shot five rounds of
32.5
33
33.5
34 (avg 2805 with an sd of 4.4 and best group)
Saw ejector swipe on all four loads. Increasing bolt lift resistance.
Kinda at a loss cause the rifle shot so well for these being the first 20 round through it.
Got my GT put together finally and took it to the range. Ran into some pressure issues that I’m thinking is brass related. Any insight would be appreciated as this is my first GT.
Rifle:
Tikka action with PVA m24 prefit at 21”
Alpha NON-OCD cases virgin
109 eldms @ 2.580 COAL .040 off the lands
32.5-34 grains of Varget
Shot five rounds of
32.5
33
33.5
34 (avg 2805 with an sd of 4.4 and best group)
Saw ejector swipe on all four loads. Increasing bolt lift resistance.
Kinda at a loss cause the rifle shot so well for these being the first 20 round through it.
I’d tone it down to 32 and put 200 rounds through it.
My barrel just now sped up at 200 rounds.
My barrel just now sped up at 200 rounds.
Switch to H4350, or RL16. I do run 109 Bergers at 2850 with rl15.5, 21in ace lt Pama 4gr 237 bore. Pressure was up around 2920 mv.
Alpha NON-OCD brass wasn't that great.
Alpha NON-OCD brass wasn't that great.
That’s my concern. Is it worth trying something different to see if it’s a brass problem since that original stuff was supposedly too soft?
I mean I'd run alpha ocd for sure stuff is tough as hell.
I’m running Alpha OCD.
On the 4th firing. Ran all 200 at 2950 twice.
Only needed trimmed after the first firing.
Fantastic brass!
On the 4th firing. Ran all 200 at 2950 twice.
Only needed trimmed after the first firing.
Fantastic brass!
So I need some opinions.
Barrel has 1730 rounds on it. Barrel is a CRB with a .170fb. Using 36.8g H4350 and Berger 109’s.
Was at a match and first 3 stages were solid then on the 4/5th stage it went to hell. The barrel sped up 15 fps and my zero was a tenth low. My velocities on this day started at 2846 and by end of day was 2861
I scrubbed it down to bare steel and went to the range. Within 30 rounds I got a crazy high flyer that was 50fps higher then the rest and my zero had shifted again a tenth low. My average velocities this day were 2840 with a single 2880 flyer.
I’m loading with an Auto trickler v4 and Alpha brass with 2 firings.
Any ideas why it’s doing this? Anyone had something similar happen?
Barrel has 1730 rounds on it. Barrel is a CRB with a .170fb. Using 36.8g H4350 and Berger 109’s.
Was at a match and first 3 stages were solid then on the 4/5th stage it went to hell. The barrel sped up 15 fps and my zero was a tenth low. My velocities on this day started at 2846 and by end of day was 2861
I scrubbed it down to bare steel and went to the range. Within 30 rounds I got a crazy high flyer that was 50fps higher then the rest and my zero had shifted again a tenth low. My average velocities this day were 2840 with a single 2880 flyer.
I’m loading with an Auto trickler v4 and Alpha brass with 2 firings.
Any ideas why it’s doing this? Anyone had something similar happen?
I have had similar issues with RL15.5ts and N150, as the barrel became more fouled velocity would increase significantly (N150) and spike 3 out of 10 shots (RL-15.5ts) after 50-60 rounds on a clean barrel. With that said, I haven't used H4350 much in the 6GT but in the cartridges that I do, it has not exhibited that type of behavior...
Assuming by "bare steel" you mean you removed any trace of carbon or copper fouling in the throat, chamber, and barrel (which you probably do... just not making assumptions - cause I've had people use that phrase to mean less than that), it sounds like you're definitely into "barrel weirdness", and I don't have a ton of experience there. A couple thoughts...
First, you might call them Okies at CRB, and see if they have useful thoughts - can't be the first time they've seen something like this.
Second - this is where I might drag out a little abrasive cleaning (I use the JB/Kroil combo - the blue lettered JB bore compound, not the red lettered JB Bore Brite), and lightly work the throat and first couple inches of barrel. The thought being that you've got some rough fire cracking in there that's collecting fouling now, and leading to weird/inconsistent pressure spikes, etc.
Third - 1700 seems pretty early for a GT tube to go south (especially at that speed and pressure - should be well south of max pressure). There's a thread here on 25x47 where guys were discussing a couple CRB barrels that also went around 1700 in that cartridge. That's hearsay, and not directly related, and I'm not at all trying to say anything remotely like "CRB barrels fail early" - just a data point to look into. I think this would also lean me toward "call CRB, and have a chat".
Oh, edit to add - I've got a Krieger straight contour tube on my GT at the moment, and it's at about the same lifepoint, but running Varget with 109s in the 2820-2840 range. It started slowing down and fouling a little more heavily - over it's life time, I've had to bump my charge a full grain to stay at speed. So maybe 1700 isn't super early? But... I hit it with the JB/Kroil thing and - if anything - velocity increased just a bit, and stopped dropping off every time I shot it. Just for whatever it's worth?
Cleaning to bare steel will always result in a speed up in the next 50-100 rounds. I used to do that, so I quit. Clean the chamber, throat, but not to bare steel, leave some the carbon staining in there. I have had much more stable velocity since I stopped over cleaning. My 65cm went 600 rounds between cleaning, speed stayed the same.
A moving zero should NOT be the result of a 15fps change. You have a scope problem, or a zero issue. Zero off a 15 shot or 2 averaged 10 shot groups to get your rifles true cone of fire.
I don't know your process, but this is mine, has worked pretty well. My last 6gt barrel went idk how many rds between cleaning, prob 500-600. Speed was 2815-2830 the entire time with half moa 10 shot groups. tlThen I though F this thing looks filthy, I better clean it, and I did, it dropped 40 fps and took about 40 rounds to come back. Haven't cleaned it since.
A moving zero should NOT be the result of a 15fps change. You have a scope problem, or a zero issue. Zero off a 15 shot or 2 averaged 10 shot groups to get your rifles true cone of fire.
I don't know your process, but this is mine, has worked pretty well. My last 6gt barrel went idk how many rds between cleaning, prob 500-600. Speed was 2815-2830 the entire time with half moa 10 shot groups. tlThen I though F this thing looks filthy, I better clean it, and I did, it dropped 40 fps and took about 40 rounds to come back. Haven't cleaned it since.
I put the same scope on my 6.5cm rifle and shot 50 rounds with 0 shift. It’s a Atacr 7-35 also.
Ran that exact combo in the womans first barrel, shot very well mid 2900s, believe it was around 33.2gr. N150 required cleaning every 120-150 rounds or it'd speed up quickly and blow the accuracy. New barrel is dtacs and H4350.
Sounds like what I'm after. I usually clean about every 60 rounds. The 107's are the best reasonably priced bullets here. Berger's are about 80% more and A-Tips slightly more than that.
The 110smk is a great bc bullet, they can be a bit picky, but they have shot well for me with a 7.5tw. Even tho sierra says is needs a 6.5 for some dang reason.
15fps shouldn’t be changing your zero/POI at 100 yards, sounds like something else is wonky to me.
I clean my barrels back to basically bare metal every 200-300 rounds, and other than it being a little annoying that it takes more than a few foulers (like ~10 or more) for the MV to re-stabilize, I don’t get any other side effects. That said, I’ve learned the hard way to not change anything as far as dope or scrutinize my zero too hard until I’ve got the thing fouled and stable again or it can get ugly, so now I just shoot 10-20 before I go putting my zero under the microscope or making adjustments (and when doing that, I almost never end up having to make any adjustments).
To me it sounds like it could be something more simple? Simple things I’d look out for is: check the torque on your action screws lately? Or, did you accidentally/unkowingly pick up some pieces of someone else’s brass that was the same headstamp at a previous match that’s now mixed into your lot (this has got me before)..? Etc… less obvious stuff you may have missed besides barrel/load?
I clean with Thorro Flush/Clean every 200-250 rounds.
After that match I got home. I checked all screws and everything was still torqued to spec. No unknown brass.
i am going to try the barrel again after the regional finale here but I’m chalking it up to maybe it just is going out early or has some weird things going on. I have a 6.5cm CRB in shooting now that shoots lights out and no issues so who knows.
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I am using 32 grains of N150 under the Berger 109 LRHT and getting great results. Mid single digit SDs and a good usable velocity of 2850. Alpha brass and CCI450 primers.
Took mine back out today and shot for more data on the barrel. At 50 rounds so curious to see where this ends up.
109s running 2755 with an sd of 8. So far I’m loving this set up.
109s running 2755 with an sd of 8. So far I’m loving this set up.
