Years ago I'd start close...like at or maybe .005 off then work back. When Mark Gordon did the seating testing in 2020 I think I had just replaced a 6BRA barrel and thought I'd try what he recommended. I started with a known load in my BRA and started seating at .050 off back to .080 off .010 at a time...I wish Ida kept the pics.....050 to .070 all shot 1 hole...not ragged but 1 hole... .080 started to open up but was a tight clover so I have been starting seating testing at .040 off every since and will work back to .080 and just about every time it ends up at .070-.080 I have never made .002-.005 jumps always .010 at a time.
- Thread starter Dthomas3523
- Start date
RIP Barrel #4. Bartlien M24 from Stuestville.
steady diet of 109 hybrids at 2840-2930 with 36.1 gr H4350.
Gave up the ghost in middle of match at around 2200.
Lesson Learned.
steady diet of 109 hybrids at 2840-2930 with 36.1 gr H4350.
Gave up the ghost in middle of match at around 2200.
Lesson Learned.
What barrel length?
So the new barrel has about .060 tho of jump from my current load of 6GT. I think it was around .030 on the last barrel. Shooting 109 hybrids.
Worth bumping the bullets out or just leave as it?
Worth bumping the bullets out or just leave as it?
I would jump as far as you can without the bullet being in the neck/shoulder junction.
If it's shoots good at 60k, leave it. My second barrel was all 109s, started at 40k jump and by 2200-2400, when puller, it was jumping around 110k at the end, and still shot well. I did have to up a half grain of powder in its life span. So I had 70k of throat erosion in it's life. Which I feel is normal for a high rate of fire 6mm running mid-upper pressure.
AFAIK .120" is SAAMI and anything different is a custom reamer order.
.120 is SAAMI but there is also a .170 reamer that’s popular my reamer will be a .274 neck and .180 freebore….if I shot 115s it would most likely be .200 I’d have to play around with the 115s to figure that out.
Love the 108s…not the highest BC but they just shoot.
RL TS 15.5 shoots well in my rifle. This is from a 7.5 twist 22" barrel. Temp was + 24 F. Shot 3 was operator error. MV and SD are for 10 shots.
That'll kill medium sized game out to quite a ways! I'm sure the 109 expands like a 108! Good shooting!
Got my criterion 26" mtu barrel on my 700 action today.
Local store only had 109 hybrids and 112 match burners.... The barnes were $100 less for 500, so I got them to try.
Going to load some from 33.8-34.8 of varget and shoot in the morning. I seated a test load at 2.6" and it chambered fine, so ill run with that for now.
Local store only had 109 hybrids and 112 match burners.... The barnes were $100 less for 500, so I got them to try.
Going to load some from 33.8-34.8 of varget and shoot in the morning. I seated a test load at 2.6" and it chambered fine, so ill run with that for now.
Found them to shoot really well 10k jump in my 120k freebore barrel. In my last 170k freebore barrels, they run well back at 60-70k jump. 2900-2920fps is what they liked with H4350 in my testing.
My CDG action is en route and 6GT PBB 26” MTU standard fb barrel has “entered production”.
The only bullet I have on hand is the 109gr ELD-M
Are there other bullets you’d recommend to have ready to try ?
Was thinking about grabbing some 105gr Hybrids.
Will be working within the col allowed by AIAW mags.
The only bullet I have on hand is the 109gr ELD-M
Are there other bullets you’d recommend to have ready to try ?
Was thinking about grabbing some 105gr Hybrids.
Will be working within the col allowed by AIAW mags.
you wont have col issues, the gt is short.
i would go with what you can get for a bullet
i would go with what you can get for a bullet
Definitely won't have OAL issues.
105 Hybrid, 107 SMK, 108 ELD-M have all done pretty well so far in my .120 freebore chamber. I bet your 109 does well too, and you might want to give those a try before you start buying other components.
Anybody running Hornady 106?
www.snipershide.com
Hornady 106gr A-tip factory seconds
I saw powder valley has 106gr tipped bullets on sale. Was told they are 106gr Atips and they're factory seconds because the firsts are for DOD 6 ARC contracts at the moment. Anyone tried these and have any results they could share?
www.snipershide.com 
I've been playing with these in a 6CM.Anybody running Hornady 106?
Hornady 106gr A-tip factory seconds
I saw powder valley has 106gr tipped bullets on sale. Was told they are 106gr Atips and they're factory seconds because the firsts are for DOD 6 ARC contracts at the moment. Anyone tried these and have any results they could share?
Haven't tried them in my 6 GT yet.
These 109gr ELDM may be the only game in town….unless I mail order.
I am glad I grabbed them when I did.
Ran by the local Cabelas & Academy earlier…..hoping to pick up some 107gr SMK and / or 105gr Hornady Match. No luck. No 6mm Bergers of any kind, either.
True that.
Planning to get my mess organized.
Once I have loads dialed in for various guns I'll know then what to maintain on my wishlists and order when prices, shipping costs, hazmat & etc are most favorable.
Looks like Midway has a couple that I wanted to try. Prices are better than some and they have free shipping at the moment.
Gonna grab some 105's to try.
Looking for some feedback. I just received my second 6GT barrel. My first one I was running Berger 109 hybrid’s with 33.2 grains of varget at 2850fps. I’m looking to slow it down to just over 2700 fps, what would you think I should start my Varget at to get close to the 2700 fps? If I had a range close to me, it would be easy but I have to drive a couple hours each way to my range. Thanks Jimmy
@Kaveman44 case fill will be very low 31-31.6 gr of varget to get your desired speed. This may results in poor es/SD. I think you'd be better off loading with a slower powder like H4831SC rl23 or N160 and keep the density up over 90-95% for consistency of ignition. Only desiring 2700-2750fps is perfect 6br country, or chop 4-6" off your current setup.
I've been running 32 grains in what seems to be a tight bore Proof barrel. I have gone as low as 31.5 grains of Varget with no ill effects. 32gr is my primary load though and yields 2830, but this barrel has also trended about 40-50 fps faster than all my previous bartlein and benchmark barrels.
I'd load up a few at 31.0, 31.5 and 32.0 with Varget, don't be afraid to jump your bullet, I seat for a .055-.060 jump with 109 hybrids and haven't had to change it for the life of three barrels now. Lately I have been doing the same with 108 elite hunters.
I am just curious why you want to slow it down to 2700 fps? What was wrong at 2850 fps?
Wouldn't heavier rounds, like 115 grain help with the goal of slowing it down?
Sorry for three questions in one post, but I am ignorant and curious, which is a bad combination.
Could be a combination of barrel life, barrel length, or just experimentation.
I ran a whole PRS season in 2022 with 6GT going 2635 with 115 DTAC. It was fun.
Curios what powder you ran for this? I am planning on going down same route, but plan run next node up mid 2700s. Was going to attempt it with a full case of Rl23.
I’m hoping to help myself see more impacts. Now with that little of a difference help, I’m not sure.
I went from 115dtac at 2860 in a gt, to 154 Berger at 2620 and I see more at low speed even with the added recoil of 65cm. That bullet is a monster in the wind too.
I thought I read that Brian Litz stated that case fill didn't affect SDs and ES as much.
I'm a huge proponent of going as slow as you can until things go to shit accuracy-wise so that you can see more.
The way I see it, we're just looking for consistent combustion, speed isn't the problem, anything ~2700fps or maybe even slower is fine if it still shoots. I don't believe in nodes, but I think there may be a tipping point where the fuel/air mix in the case isn't where it needs to be and where things may get wonky, and that's probably what we need to look out for when figuring out how slow one can go...
I just put on a new barrel and it's running ~2850fps after only 60rds through it (so it'll likely speed up a bit more, and I haven't decided if that's too fast for me yet). This is with 33gn of Shooters World Precision Rifle (aka Lovex SO62, Varget-alike) and a 106gn A-Tip. I had been getting ~2800-2750fps with the same 33gn SWPR and a 112 Match Burner, and that seemed to be great for helping my brain catch up with my eyes inside 600 yards. So I may slow things down.
I'm on the fence about how much case fill effects SD/ES as I've never gone higher than 34gn of SWPR in the 6GT and have went down to 32.5gn and my SDs stayed pretty consistent at ~6.0 (sometimes stupid low like SD 1-2 over 5 shots when checking it now and again). Ds of 1 over
The way I see it, we're just looking for consistent combustion, speed isn't the problem, anything ~2700fps or maybe even slower is fine if it still shoots. I don't believe in nodes, but I think there may be a tipping point where the fuel/air mix in the case isn't where it needs to be and where things may get wonky, and that's probably what we need to look out for when figuring out how slow one can go...
I just put on a new barrel and it's running ~2850fps after only 60rds through it (so it'll likely speed up a bit more, and I haven't decided if that's too fast for me yet). This is with 33gn of Shooters World Precision Rifle (aka Lovex SO62, Varget-alike) and a 106gn A-Tip. I had been getting ~2800-2750fps with the same 33gn SWPR and a 112 Match Burner, and that seemed to be great for helping my brain catch up with my eyes inside 600 yards. So I may slow things down.
I'm on the fence about how much case fill effects SD/ES as I've never gone higher than 34gn of SWPR in the 6GT and have went down to 32.5gn and my SDs stayed pretty consistent at ~6.0 (sometimes stupid low like SD 1-2 over 5 shots when checking it now and again). Ds of 1 over
Varget
I must have a snail barrel lol I’m at 32.8 grains of Varget at 2815. That’s with an MPA match barrel has 200rnds down it with 109’s
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I’m gonna load up 10 rounds each of 31 grains , 31.5 grains, and 32 grains and see where my SD’s are as well as MV. I should be close to my 2700 fps with all these since I’m at 2850 fps at 33.2 grains. Thanks Guys
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I ran my GT last season at 2775 with the DTACS and felt it was as smooth as can be. My load this year so far is DTACS at 2810 and have zero problems spotting shots or trace. At least when this damn mirage will allow it. Last two matches have had the worst mirage I’ve ever shot in.
It's that time of year. Mornings here are in the 20s, mid day its 55-65° and mirage is like pea soup, thick af.
I don't have a lot of hope for barrel longevity in my 6GT, but it is a fun project. I started out with 100 rounds of factory Eagle Eye 105gr Hybrids. After a slight seating depth tweak (was getting 4+1groups), I shot 3 consecutive 5-shot groups that agg'd about .4 even. Ran the last 5 over a chronograph after about 125 rounds down the tube - 2,964 with an ES of 12 and an SD of 4. Too bad that stuff is so expensive. But I got the Alpha brass to mess with. **27" Krieger barrel **
I already knew the factory load was pretty warm. It only took 3.6 mils to get to 655, so I had figured 2,950 anyway. So I started load development with that velocity in mind.
1,600 rounds and then I'll pull the barrel is kind of my goal. At this point I don't think I'll do another 6GT anytime soon. I love the efficiency of the round, but I've had feeding issues in both of my AI mags. I did try chambering a few in my 6.5x47 FN SPR...and the 10 attempts worked fine, maybe because of the CRF, or maybe I just got lucky.
I bet there's probably a good lower velocity window, but not being hugely invested in this round I'm not really concerned with barrel life. FWIW, the most this barrel sees at a time is 10 rounds...maybe 25-30 over a half-hour load development session.
I already knew the factory load was pretty warm. It only took 3.6 mils to get to 655, so I had figured 2,950 anyway. So I started load development with that velocity in mind.
1,600 rounds and then I'll pull the barrel is kind of my goal. At this point I don't think I'll do another 6GT anytime soon. I love the efficiency of the round, but I've had feeding issues in both of my AI mags. I did try chambering a few in my 6.5x47 FN SPR...and the 10 attempts worked fine, maybe because of the CRF, or maybe I just got lucky.
I bet there's probably a good lower velocity window, but not being hugely invested in this round I'm not really concerned with barrel life. FWIW, the most this barrel sees at a time is 10 rounds...maybe 25-30 over a half-hour load development session.
$260 for 100 rounds, wow!
Yeah, not cheap. I bought it when my barrel came in and there was zero Alpha brass, or Hornady loaded ammo available. I figured I'd break the barrel in and find a seating depth preference for the 105 Hybrid while I was at it. Turns out that it was a hammer of a load after a small tweak...but I'm not making a habit of paying $2.60/round for something that I shoot as a hobby.
What was the small tweak?
.005 in, nothing else. Went from three consecutive 4+1 groups to this for three consecutive groups:
