6GT project/range report
- Thread starter NorCalVu
- Start date
Got the 6gt up and running. So far I really like it. Chopped the barrel to 24" instead. These are the first loads down the tube. First pic is 32.5 grs of 4166. 2801FPS, SD 9.29, ES 22. Second pic is 40.5 grs of Superformance. 2924FPS, SD 13.5, ES 30. Feeds fine from Magpul and MDT mags.
Attachments
Started load development on my 6GT F-Open last weekend. After achieving a pretty good score while running the barrel in with 105gr Lapua Scenars at a leisurely 2900fps at 400 metres and only dropping 1 point, I was pretty confident about finding a nice load with Berger 109gr hybrids...Well after todays trip to the range it looks like I still have some work to do!
I spent a good 3 hours at the range and put another 50 rounds of the Lapua's downrange - this brought the barrel round count up to 116. Gave the barrel a clean and set about trying to find a load with the Berger's (these things look downright sexy compared to the Lapua's).
Rifle details are:
Borden BRMXD action
Bartlein 32" 5R 8 twist truck axle barrel with a Dan Bramley tuner (won't be touching this just yet)
Brass: Alpha OCD once fired, annealed with case mouths chamfered and deburred
Powder: ADI2209 (H4350)
Primer: CCI BR4
Projectile: Berger 109gr hybrid jumped 15 thou (I wasn't shooting for groups though at an indoor range).
All loads shot over 5 shot groups with a Labradar.
36.5gr - Average velocity 2902fps, ES = 18 and SD = 5
No pressure signs but velocity was obviously a low starting point
36.8gr - Av velocity 2936fps, ES = 18, SD = 7.3
Still down on velocity from where I'd like this project to end up
37.1gr - Av velocity 2965fps, ES = 28, SD = 11.6
Starting to climb a bit now - no pressure signs and cases fell out easily
37.3gr - Av velocity 2993fps, ES = 28, SD = 10.8
Still no signs of pressure
37.5gr - Av velocity 3009fps, ES = 12, SD = 4.5
This load data looks promising and is probably worth some further testing. Still no signs of pressure and cases fell out easily on extraction
37.7gr - Av velocity 3023fps, ES = 15, SD = 6.1
Still no signs of pressure
So after the first powder charge run, I was left in a little bit of a quandary - the 37.5gr load shows some potential, but I'm sure it's capable of better. I have a good supply of S&B small rifle primers which I think I may test to see if they don't tighten things up a bit more than the CCI BR4s. Due to the primer shortage, I don't have the option of trying anything other than these 2 primers.
I'm also wondering whether to climb around the 38gr mark to see if things tighten up there as 37.7gr was still easy on the brass and bolt lift on extraction was nice and smooth with minimal effort.
I haven't seen any real data out there on the 109gr Berger in long barrel setups like mine so I have no idea if I've hit the node, or still need to climb a little higher.
Whilst it's early days I'm liking it so far. If I can bed down the powder charge next weekend, then I'll move onto seating depth testing. Has anyone got the 109s humming?
UPDATE:
Went at it again today, this time taking the powder charge up a bit higher, and testing whether primers would make much of a difference to my load data...So I ran CCI BR4 and S&B primers side by side with the same powder charge and this is what I got:
37.5gr with CCI BR4: Av velocity 2992fps, ES=16, SD=7 (wanted to run this one again as it was the best one from Saturday, this one was shot off a clean barrel)
37.5gr with S&B: Av velocity 2995fps, ES=12, SD=5.2 (no pressure signs with either primer)
37.9gr with CCI BR4: Av velocity 3039fps, ES=18, SD=7
37.9gr with S&B: Av velocity 3032fps, ES=13, SD=5 (no pressure signs with either primer)
38.1gr with CCI BR4: Av velocity 3066fps, ES=45, SD=17.6
38.1gr with S&B: Av velocity 3052fps, ES=11, SD=4 (no pressure signs with either primer)
38.3gr with CCI BR4: Av velocity 3089fps, ES=31, SD=12.7
38.3gr with S&B: Av velocity 3074fps, ES=8, SD=3.9 (still no pressure signs)
38.5gr with S&B: Av velocity 3097fps, ES=29, SD=12.5
I didn't bother with the CCI BR4 on the last charge as the S&B consistently shot inside of it at all other powder charges, and it was obvious at 38.5gr I was outside the node as things opened up again.
The goal of this project was to see if I could obtain Dasher levels of velocity and accuracy. After chatting to a couple of mates last night who run Dashers with 2209 (H4350), they have nodes at 3050fps, which coincidentally also seems to be the case with the 6GT. So I'm going to look at running the 38.1gr charge with S&B primers, and work on seating depth, followed by the tuner. The velocity is certainly there, now let's see if the accuracy is!
I spent a good 3 hours at the range and put another 50 rounds of the Lapua's downrange - this brought the barrel round count up to 116. Gave the barrel a clean and set about trying to find a load with the Berger's (these things look downright sexy compared to the Lapua's).
Rifle details are:
Borden BRMXD action
Bartlein 32" 5R 8 twist truck axle barrel with a Dan Bramley tuner (won't be touching this just yet)
Brass: Alpha OCD once fired, annealed with case mouths chamfered and deburred
Powder: ADI2209 (H4350)
Primer: CCI BR4
Projectile: Berger 109gr hybrid jumped 15 thou (I wasn't shooting for groups though at an indoor range).
All loads shot over 5 shot groups with a Labradar.
36.5gr - Average velocity 2902fps, ES = 18 and SD = 5
No pressure signs but velocity was obviously a low starting point
36.8gr - Av velocity 2936fps, ES = 18, SD = 7.3
Still down on velocity from where I'd like this project to end up
37.1gr - Av velocity 2965fps, ES = 28, SD = 11.6
Starting to climb a bit now - no pressure signs and cases fell out easily
37.3gr - Av velocity 2993fps, ES = 28, SD = 10.8
Still no signs of pressure
37.5gr - Av velocity 3009fps, ES = 12, SD = 4.5
This load data looks promising and is probably worth some further testing. Still no signs of pressure and cases fell out easily on extraction
37.7gr - Av velocity 3023fps, ES = 15, SD = 6.1
Still no signs of pressure
So after the first powder charge run, I was left in a little bit of a quandary - the 37.5gr load shows some potential, but I'm sure it's capable of better. I have a good supply of S&B small rifle primers which I think I may test to see if they don't tighten things up a bit more than the CCI BR4s. Due to the primer shortage, I don't have the option of trying anything other than these 2 primers.
I'm also wondering whether to climb around the 38gr mark to see if things tighten up there as 37.7gr was still easy on the brass and bolt lift on extraction was nice and smooth with minimal effort.
I haven't seen any real data out there on the 109gr Berger in long barrel setups like mine so I have no idea if I've hit the node, or still need to climb a little higher.
Whilst it's early days I'm liking it so far. If I can bed down the powder charge next weekend, then I'll move onto seating depth testing. Has anyone got the 109s humming?
UPDATE:
Went at it again today, this time taking the powder charge up a bit higher, and testing whether primers would make much of a difference to my load data...So I ran CCI BR4 and S&B primers side by side with the same powder charge and this is what I got:
37.5gr with CCI BR4: Av velocity 2992fps, ES=16, SD=7 (wanted to run this one again as it was the best one from Saturday, this one was shot off a clean barrel)
37.5gr with S&B: Av velocity 2995fps, ES=12, SD=5.2 (no pressure signs with either primer)
37.9gr with CCI BR4: Av velocity 3039fps, ES=18, SD=7
37.9gr with S&B: Av velocity 3032fps, ES=13, SD=5 (no pressure signs with either primer)
38.1gr with CCI BR4: Av velocity 3066fps, ES=45, SD=17.6
38.1gr with S&B: Av velocity 3052fps, ES=11, SD=4 (no pressure signs with either primer)
38.3gr with CCI BR4: Av velocity 3089fps, ES=31, SD=12.7
38.3gr with S&B: Av velocity 3074fps, ES=8, SD=3.9 (still no pressure signs)
38.5gr with S&B: Av velocity 3097fps, ES=29, SD=12.5
I didn't bother with the CCI BR4 on the last charge as the S&B consistently shot inside of it at all other powder charges, and it was obvious at 38.5gr I was outside the node as things opened up again.
The goal of this project was to see if I could obtain Dasher levels of velocity and accuracy. After chatting to a couple of mates last night who run Dashers with 2209 (H4350), they have nodes at 3050fps, which coincidentally also seems to be the case with the 6GT. So I'm going to look at running the 38.1gr charge with S&B primers, and work on seating depth, followed by the tuner. The velocity is certainly there, now let's see if the accuracy is!
Found a pretty good node with 38 grains of IMR 4350. Compressed load. 2967 fps, ES of 16. 10 shots in the main group. The two outside were cartridges I put in hot water to check temp sensitivity. It was 40 degrees out when i shot this. Those two shots registered 3030 and 3070 fps but there were no symptoms of high pressure at all. I'd say that IMR 4350 is 95%+ case fill. I dont think you can put enough IMR in the case to hit over pressure.
Attachments
Anyone have experience with a 16" barreled 6GT? Im thinking of 85gr barnes bullets at 2900 fps. Want to build a general purpose hunting gun for my 7yr old to hunt with me. Right now he shoots my 6.8spc AR, but i want a bolt gun for him.
Uhh, from a 16" barrel? He's gonna whack deer and pigs with it. Maybe a squirrel also.
Clancy
Silver $$ Contributor
I think REALLY short barrels are crippling to cartridges of that size. I’ve seen many a “x47 Lapua” ruined with a 16” barrel. I’d look at a 6BR, without a doubt. I have a 20” that runs 68 avengers 3350 with a lot of room left. I’d imagine a premium 80 grain would be a riot. I don’t understand the 16” thing at all, but it’s not for me to understand.
I agree that 6 BR would be a better choice, especially for a 7 year old.
16" barrels make sense because we hunt like civilised people, suppressed only. And my kid is like 55lbs, so lighter and shorter is mo better. Hell, I might carry it if I like it. Not taking on 6br, probably negligible recoil difference and I'm already fully geared up for 6GT, 6.8spc, 5.56, and 300blk.
Lol. Thanks for the totally unrelated link.
No one seems to have any actual numbers for shorter than competition length 6gt barrels. I'll post mine when the project is done.
No one seems to have any actual numbers for shorter than competition length 6gt barrels. I'll post mine when the project is done.
no because it is the WRONG choice.
a 6br with your bullet....try 18" with a smaller profile to maintain weight.
I'm convinced, ill drop $1000 to get setup in 6br and stop being dumb with my gt.
you will have to explain why it will cost $1000 to get set up if you currently shoot a 6 ???
I'm moving on.
Upgrades & Donations
This Forum's expenses are primarily paid by member contributions. You can upgrade your Forum membership in seconds. Gold and Silver members get unlimited FREE classifieds for one year. Gold members can upload custom avatars.
Click Upgrade Membership Button ABOVE to get Gold or Silver Status.
You can also donate any amount, large or small, with the button below. Include your Forum Name in the PayPal Notes field.
To DONATE by CHECK, or make a recurring donation, CLICK HERE to learn how.
Click Upgrade Membership Button ABOVE to get Gold or Silver Status.
You can also donate any amount, large or small, with the button below. Include your Forum Name in the PayPal Notes field.
To DONATE by CHECK, or make a recurring donation, CLICK HERE to learn how.