Range Report 6GT Project/Range Report
- Thread starter NorCal Vu
- Start date
id run 35-35.2-35.4 3 shot groups and id probably start .005 off the lands...the few 109s i shot in my BRA grouped best at .010 off not so good at .020 off.
and yes erik makes things simple.
Awesome. Thanks for the info. Who made your barrel if you dont mind? I have a PVA on the way
It’s a bartlein blank chambered with my 6gt reamer by Enrique at Massey’s Gunshop.
@trophyhunter would be the contact on here for them.
Here is 34.0 with virgin brass and barrel.
Awesome. I was planning on starting at .005 and using .003 increments up to .040
Well add me to the Gay Tiger pride. Called my gunsmith today and will be having a barreled action spun up for a a comp rig.
I’ll have some virgin alpha brass velocity data with 109’s and varget tomorrow. 32.0-36.0 in .2gr increments. Normally I stick to .5’s, but I need to get about 250pcs fired for a match next week. Might as well break the data down further.
Just in brass prep, I’m seeing pretty noticeable consistency differences vs hornady brass.
Alpha neck thickness is more consistent and not tapered like Hornady
When prepped the same I’m seeing about half the seating pressure ES in alpha vs Hornady. Alpha ~10-12psi and Hornady ~20-25psi
Alpha seems a bit harder than Hornady. I have to go a little slower in my Giraud when initially trimming to uniform length.
I’m getting low two digit and single digit ES with hornady brass. Worst being 20fps ES.
Based on what I’m seeing from brass prep numbers, Alpha should at least be that good.
Just in brass prep, I’m seeing pretty noticeable consistency differences vs hornady brass.
Alpha neck thickness is more consistent and not tapered like Hornady
When prepped the same I’m seeing about half the seating pressure ES in alpha vs Hornady. Alpha ~10-12psi and Hornady ~20-25psi
Alpha seems a bit harder than Hornady. I have to go a little slower in my Giraud when initially trimming to uniform length.
I’m getting low two digit and single digit ES with hornady brass. Worst being 20fps ES.
Based on what I’m seeing from brass prep numbers, Alpha should at least be that good.
I'm running a 26 inch barrel, 1/7 twist, 109 berger, Varget, CCI 450 and fresh alpha brass. I didn't prep the brass at all but I wonder how close your data will compare to mine. I use Magnetospeed v3 and auto trickler v3 so my measurement and data is kinda decent. 
What was your ES like? Here is my once fired hornady data. But I take brass prep further than I need to.
Large numbers on graph is the fps difference between charges.
10 rounds with 34.4, 2878 avg, 2885 max, 2868 min, es 17 and sd 5.0. I did my latter test with less than 100 rounds and decided to go with 34.4 as the charge weight. I now have 280 rounds down the tube and its moved up a little in speed to 2891. All done with virgin brass. Strelok pro says my BC is .31 and I'm at 715 yards with 4.5 mils. Barrel is PVA with no pressure signs, bolt lift remained the same and brass looks fine.
I have 2 GT's both are 26inchs in length shooting hornady brass and 105 hybrids 1 of them is a Proof steel MTU 7.5T with 900 rounds on it, and the other is a Benchmark MTU 7.5T with 500 rounds on it. I'm shooting Varget and CCI450's the Proof likes 34.8 grains at 3003 fps and the Benchmark is at 34.2 at 3028. The SD and ES are very low on both barrels. I've took 100 hornady brass and fired them 6 times and have yet to loose 1 any due to bad primer pockets. The way I figured it was if I start with 300 pieces hornady brass per barrel and I can get 8 firings per piece. I would have fired 2400 rounds down the barrel and it should be wore out. Throw it all away and start fresh on the next. Just my 2 cents.
Ar sea level Applied Ballistics puts you closer to .290-.295. I have several buddies running these and we have all ended up around .292-.296 truing from 300-1100 using 7 and 7.5 t barrels.
Here is virgin alpha brass. I need to get brass fired for brawl. So did 5 shot groups in .2 increments since I was gonna be shooting them all day.
26” 1:7 bartlein chambered by Enrique at Masseys Gunshop (@trophyhunter
All with varget and 109 Bergers .020 jump
Brass prep:
Brass trimmed to uniform length
Necks uniformed to .012
Necks sized back down with .263 bushing
.242 mandrel back up (~.001 spring back)
Checked with .241 pin gauge
Chamfer/debur
Seated with hydro press ~40psi with ~12 ES
The truing bar is 34.0 as that’s what I run on virgin brass at matches. Wind was switching from straight up to 1.2mil. So only focused on vertical which was around 3-4”
Distance to truing bar was 933 yds
26” 1:7 bartlein chambered by Enrique at Masseys Gunshop (@trophyhunter
All with varget and 109 Bergers .020 jump
Brass prep:
Brass trimmed to uniform length
Necks uniformed to .012
Necks sized back down with .263 bushing
.242 mandrel back up (~.001 spring back)
Checked with .241 pin gauge
Chamfer/debur
Seated with hydro press ~40psi with ~12 ES
The truing bar is 34.0 as that’s what I run on virgin brass at matches. Wind was switching from straight up to 1.2mil. So only focused on vertical which was around 3-4”
Distance to truing bar was 933 yds
Attachments
Last edited:
Alpha shoulders only moved about .003
So fired brass velocity should be pretty close
To virgin
So fired brass velocity should be pretty close
To virgin
Also have found this to be a good training exercise. The velocity increase over time with powder charge makes POI move up. Also makes wind hold less. And I have a magnetospeed chrono bayonet strapped to barrel. So that changes harmonics/poi.
I don’t care what the groups are like at this point as I’m looking at chrono numbers for consistency within powder nodes.
So, I use it as atraining exercise. Set target at 900+.
On every trigger pull, pin the trigger back and hold until you
See the impact. If you hit, keep holding until you hear the steel ring.
If you miss, make them correction and go again
105 rnds of good training while collecting data.
I don’t care what the groups are like at this point as I’m looking at chrono numbers for consistency within powder nodes.
So, I use it as atraining exercise. Set target at 900+.
On every trigger pull, pin the trigger back and hold until you
See the impact. If you hit, keep holding until you hear the steel ring.
If you miss, make them correction and go again
105 rnds of good training while collecting data.
Good to know I went with alpha too
those numbers are pretty consistent with my ole 6x47 numbers
Whats barrel life on 6x47? Serious question
I've roasted six 6x47 barrels and I'd say way too many variables to answer that question accurately.
Not sure how it’s relevant. The question was about 6x47. So that once 6gt barrels start going we can compare.
What was the least and what was the most?
I had 6cm go anywhere from 900 to 1700 rnds. Tis why I working on dasher and gt to see how much of an improvement it is.
Gimme a break. You were all over the "Best 6mm" thread so for starters you're asking a question to which the answer has been already discussed.
Kinda seems like you're throwing the Tigger's barrel life around but maybe I'm just misreading. I found it humorous given nobody knows what the barrel life is yet.
Lol......kinda seems like you should read better.
I ran 105 hybrids with 35gr varget @ 3020-3040 in my 47s. My guess is the GT will be in that same range if using the same powder charge and getting the same velocities.
Going to see my smith this week and get a 6GT barrel on order. I know it will be a 26 inch heavy varmint, but I'm uncertain about the twist. What are the advantages/disadvantages between a 7 and a 7.5 twist? Or is it enough to worry about?
Won’t matter. The only difference I’ve seen is a slight improvement in BC on the 105 hybrids going from a 7.5 to 7. Right around 2%.
Just loaded up a couple of ladder tests.
110 A Tips
Base to O-Give: 1.985
Jump: 0.035
Brass: Hornady
Primer: FGM105M
Neck: 0.241 expander
Three of each charge
1) 33.8
2) 34.0
3) 34.2
4) 34.4
5) 34.6
109 Hybrid
Base to O-give: 1.956
Jump: 0.025
Brass: Hornady
Primer: FGM105M
Neck: 0.241 expander mandrel
Five of each
1) 33.4
2) 33.5
3) 33.6
4) 33.7
5) 33.8
Had some light ejector swipe today in the 34.5gr range but I was loading real close to the lands. Going to try the lower node just to see what happens.
I'll update when I go out next weekend.
110 A Tips
Base to O-Give: 1.985
Jump: 0.035
Brass: Hornady
Primer: FGM105M
Neck: 0.241 expander
Three of each charge
1) 33.8
2) 34.0
3) 34.2
4) 34.4
5) 34.6
109 Hybrid
Base to O-give: 1.956
Jump: 0.025
Brass: Hornady
Primer: FGM105M
Neck: 0.241 expander mandrel
Five of each
1) 33.4
2) 33.5
3) 33.6
4) 33.7
5) 33.8
Had some light ejector swipe today in the 34.5gr range but I was loading real close to the lands. Going to try the lower node just to see what happens.
I'll update when I go out next weekend.
Be careful with this - I did same in a similar situation, and it weakened the shell holder enough that it bent when pulling a case out of a size die (not a stuck case - just normal sizing)
Checking dope for match this weekend. 933yds. That’s reason for only a couple shots as I’m in a crunch to get back and load 250rnds.
1x fired alpha, 109’s, 34.0 Varget. .020 off lands.
AB says it’s around 2950 to match their CDC.
I don’t chrono for dope as to not mind fuck myself before a match. So I’m not sure what the exact speed is. I’ll check next week.
Will have 700+ rnds on barrel by Sunday.
1x fired alpha, 109’s, 34.0 Varget. .020 off lands.
AB says it’s around 2950 to match their CDC.
I don’t chrono for dope as to not mind fuck myself before a match. So I’m not sure what the exact speed is. I’ll check next week.
Will have 700+ rnds on barrel by Sunday.
What velocity difference did you see between once fired and virgin brass for the same powder charge?
So, had some serious bolt lift issues that caused me to stop shooting a match over the weekend. Started out clicking and ramped up to beating my bolt open. Was running a mild 34.0 varget with 109’s at 2950 ish. .020 off lands.
After checking measurements and making sure my sizing die was sizing all the way down the base, I took ejector out of my bolt and noticed it would not close with just gravity like it should with a jump.
Pulled bullet and it fell closed on brass (I size mine for a free fall without a small crush like some like). Seated bullet again and same thing. No drop.
Ended up having to seat bullet another .030 for a total of .050 jump for bolt to free fall.
I’m waiting on a new borescope this week, so the attached picture sucks. But it’s a very bad carbon ring that was turning my .020 jump into a jam. I was running mild enough pressure to not blow primers, but still swell the cases out and have hard extraction.
It took quite a while to brush it out (and still have some cleaning to do), and now all my .020 loaded ammo allows the bolt to fall. A few get hung at the very bottom, so there’s still a bit of a ring in there.
This was at 490 rnds without cleaning. I’m sure it’s not indicative of other 6gt barrels. Just sharing my experience.
This is what can happen if you only clean once “accuracy starts degrading.” The rifle was still shooting .3/.4moa and dope was lining up as expected.
After checking measurements and making sure my sizing die was sizing all the way down the base, I took ejector out of my bolt and noticed it would not close with just gravity like it should with a jump.
Pulled bullet and it fell closed on brass (I size mine for a free fall without a small crush like some like). Seated bullet again and same thing. No drop.
Ended up having to seat bullet another .030 for a total of .050 jump for bolt to free fall.
I’m waiting on a new borescope this week, so the attached picture sucks. But it’s a very bad carbon ring that was turning my .020 jump into a jam. I was running mild enough pressure to not blow primers, but still swell the cases out and have hard extraction.
It took quite a while to brush it out (and still have some cleaning to do), and now all my .020 loaded ammo allows the bolt to fall. A few get hung at the very bottom, so there’s still a bit of a ring in there.
This was at 490 rnds without cleaning. I’m sure it’s not indicative of other 6gt barrels. Just sharing my experience.
This is what can happen if you only clean once “accuracy starts degrading.” The rifle was still shooting .3/.4moa and dope was lining up as expected.
Last edited:
I had a real bad carbon ring with my 6.5 after at about 4-500 rounds like that. All of a sudden everything felt like it was getting jammed in the lands.
since then I clean my barrels after every match. I don’t wanna deal with a carbon ring again.
since then I clean my barrels after every match. I don’t wanna deal with a carbon ring again.
Same. I ordered a bunch of cleaning supplies and better borescope to validate clean barrel.
I’ll be cleaning after every match and fouling with a few rounds a few days before a match. The most I will go from now on is 250 rounds or so if it’s a 2 day match.
ive only had 1 carbon ring in all the barrels ive shot and it was just starting nothing like you guys have had and why i do not go more than 200ish(and most times 100- 150 rounds)before cleaning....also why i try to run my necks close to the neck grove cut by the reamer.
this is where these come in handy...
this is where these come in handy...
I like that. Just had your smith make it?
Guy shooting on my squad had a similar problem started getting heavy bolt lift
And ended up blowing a primer
I had a couple of boresnakes in my bag
We pulled them through the barrel several times and he was able to finish the match not optimal but it saved his day
I try to clean every 200 RDS.
Got Stub? Barrel Stub Gauges Serve Many Functions « Daily Bulletin
Next time you have a barrel fitted, consider having your gunsmith create a stub gauge from a left-over piece of barrel steel (ideally taken from your new barrel blank).
Some date points on my new Benchmark 26" barrel using New Hornady brass, 33.5 Varget CCI 450 primers and 105 Hybrids jumped .020"
My first three shots through the new barrel averaged 2852.
At round count 64 it had sped up 32 fps.
At 161 rounds I am now 22 fps faster for a total gain of 54fps from new and gains have slowed considerably.
Time to start serious load development.
Once fired Hornady brass, Varget, CCI450's and 109 Hybrids jumping .025"
My first three shots through the new barrel averaged 2852.
At round count 64 it had sped up 32 fps.
At 161 rounds I am now 22 fps faster for a total gain of 54fps from new and gains have slowed considerably.
Time to start serious load development.
Once fired Hornady brass, Varget, CCI450's and 109 Hybrids jumping .025"
Anyone buy Alpha brass lately? This is my first experience with Alpha and the case heads seem really soft. I did barrel break-in with 100 rounds of Varget at 32.5, 205M's, and 105 hybrids 10 thou off.. I can see faint extractor imprints. Not swipes or anything and the primers show no signs of pressure.
I'm getting alot of brass transfer to the bolt face as well.. it's strange.
Going to try some H4350 on the lighter side next.
I'm getting alot of brass transfer to the bolt face as well.. it's strange.
Going to try some H4350 on the lighter side next.
Not meaning to derail the thread, but what program is that?
It’s a spreadsheet for load development that the 65 Guys made. It’s really handy.
You can find it here.
Load Development Analysis
Determination of the optimal load for your rifle necessarily includes some form of analysis. In this episode we cover load development analysis – as a follow-up to the very popular 6.5 Guys L…
www.65guys.com 
