I personally don't think the modbb is worth it. The cost savings of a couple hundred rounds with the added $$$ over standard steel (and availability) isn't worth it.
6gt
- Thread starter Dthomas3523
- Start date
NiteQwill: I'm curious to know if you have any actual data to support "a couple hundred rounds"?
Personal information with frequent people I shoot with (high round match shooters). Guinea pigs with modbb barrels in 6mm. Not one of them is buying another. Example of a 2700 round count Dasher barrel pull. Not worth it to me at the extra cost. I can buy one extra barrel for every 3 modbb barrels and shoot more rounds overall.
Take it as you see it. Ymmv.
2 or 3 guys I shoot with running 400Mod steel are well north of 2500 rounds and still hammering.
In a conversation with Bartlein they stated in their testing that 3500 wasn't an unreasonable.
Time will tell I guess. If the couple guys I know running it in 6BR and 6GT are a testament, then they're well on their way.
In a conversation with Bartlein they stated in their testing that 3500 wasn't an unreasonable.
Time will tell I guess. If the couple guys I know running it in 6BR and 6GT are a testament, then they're well on their way.
Well the numbers we are hearing were twice the barrel life so that's about 5-6000K for a BR or GT.
If you aren't getting that that the extra cost may not be worth it. Its ~ 25% cost increase on a chambered barrel so you would have to get atleat 3100 with the GT or 3750+ with the BR for the cost to even make it worth it.
If you aren't getting that that the extra cost may not be worth it. Its ~ 25% cost increase on a chambered barrel so you would have to get atleat 3100 with the GT or 3750+ with the BR for the cost to even make it worth it.
I have only run H4350 with 109's since the beginning and nothing else.
That’s one of the main reasons I picked up a GT barrel. In these days of component and powder shortages I liked the idea of a cartridge that can use 4350 or Varget class powders.
Definitely not worth arguing with someone about whether or not they believe in throat erosion
No one said they they don’t believe in throat erosion.
There is however the erosion into the lands and the erosion at the neck/throat junction. These are not necessarily linear and have different effects on performance.
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Well, I may just keep sitting 6GT until my components run out.
He's going .308 boys, you watch.
It's gunna make a comeback
It is amazing that we have been shooting rifles for 100+ years and we still don’t have definite answers on this. I load close to the lands, purely for accuracy, but if you could get an extra however many rounds of match accuracy out of a barrel by jumping (spacewalking?) then I would try it. It seems the trends in reloading and in cartridge selection is forever going around in one big circle. The 6GT is really just a Swiss Match or a 6x44 with a name behind it, good to see people trying different shit anyway.
Jumping more won’t degrade a barrel less as that’s not what kills a barrel. At least not the velocity part. It’s the end of the neck area. Once that starts heavily degrading, you will lose velocity and then won’t be able to predict the next velocity loss or when it’s just too far gone.
The lands being eroded will be what affects precision (mostly). And you can keep changing them until they are just too far gone or the firecracking is just too much.
That’s why you see some toss a barrel when velocity takes a hit, and others will up the charge and keep chasing until precision falls off. Both are valid strategies if utilized in the proper way.
As far as long jump, that’s not for barrel life. That’s for the longest amount of rounds before precision or POI changes enough to affect your performance.
And it’s fairly well known that jumps are not as precise as loading into the lands. Otherwise BR shooters wouldn’t almost universally be loading into lands.
The difference is the amount of shots taken in a match. A PRS match plus match prep can be 300 rounds or so.
So, we make a trade. We trade some precision for longer round count before a *possible* degradation in accuracy enough to cause problems. And our target size is large enough the trade of precision doesn’t really matter.
Simply put, if you desire .2 precision, you will need to be close to or into the lands. But you will have to keep an eye on it.
If you desire .5, then you can load further away and let it eat for a while.
Either way, if you’re just shooting with a bipod and a rear squeeze bag, .2’s is all but impossible long term.
Sarcastic comment time:
WOW it's almost like the enginerds at the bullet and ammo companies know a thing or two about bullet jump when recommending SAAMI overall lengths
Sarcasm/
But, seriously, that's a fantastically logical explanation of consistency across different lengths of jump to the lands.
Sarcastic comment time:
WOW it's almost like the enginerds at the bullet and ammo companies know a thing or two about bullet jump when recommending SAAMI overall lengths
Sarcasm/
But, seriously, that's a fantastically logical explanation of consistency across different lengths of jump to the lands.
Thanks. And I could be completely wrong. But I can’t come up with a better theory. And I’ve spent way more hours awake at night thinking about it or conversing with others.
I think a big part of what’s missing on our end on the practical shooting side is asking:
- why do something
- how often do we need to do it
- what is our precision requirement
- what is our precision capability
Cause, let’s be honest, it would be very easy to load into lands (not enough to stick a bullet) and be done with it. But will that last 300 rounds before you start missing targets?
Same with the things like primer seating “nodes.” Let’s forget the debate and assume that is a real thing.
If you’re not using a neo rest or equivalent (or better)……it’s virtually impossible to consistently hold a rifle still enough to exploit that advantage.
I am no expert in reloading by I try to read alot and listen to those who shoot the best. They already have it figured out so no reason to try and reinvent the wheel, or at least that's the thought process.
Now this may be bullet design dependent but it appears many bullets shoot better when they are jumped. That old jam them into the lands is quickly becoming an old wives tale.
Here is some of the of the articles that include the testing Litz and Marc Gordon did along with a recent podcast where Satterlee talks about super long freebores shooting better with high jumps
precisionrifleblog.com
precisionrifleblog.com
precisionrifleblog.com
It might behoove folks to read though and watch that video and see if its changes their view on some things.
Now this may be bullet design dependent but it appears many bullets shoot better when they are jumped. That old jam them into the lands is quickly becoming an old wives tale.
Here is some of the of the articles that include the testing Litz and Marc Gordon did along with a recent podcast where Satterlee talks about super long freebores shooting better with high jumps
Bullet Jump & Seating Depth: Best Practices & Conventional Wisdom
With so many events canceled and stores closed, what a great time to do some reloading! Over the pa...
precisionrifleblog.com
Bullet Jump: Is Less Always Better?
About 2 years ago, Mark Gordon shared some preliminary research he’d conducted with the Applied Bal...
precisionrifleblog.com
More Bullet Jump Research!
This is the 4th article in a series on some new research on bullet jumps. Here is a recap of the pr...
precisionrifleblog.com
It might behoove folks to read though and watch that video and see if its changes their view on some things.
@DeathBeforeDismount the best absolute pinpoint accuracy with most custom match bullets is found +10 to -20 seating depth. Talk the benchest and F class guys and they will tell you this. Keeping things tuned here is much more finicky as the purest accuracy may have a small 002-003 seating depth window. The windows further back off the lands are usually quite a bit wider/more forgiving but aren't as good of accuracy. Still good accuracy, but not the stuff that breaks records at 600 and 1k yards. This info has come from some the guys that are very competitive at the deep creek 1k nationals held a few hours south of me.
I am no expert in reloading by I try to read alot and listen to those who shoot the best. They already have it figured out so no reason to try and reinvent the wheel, or at least that's the thought process.
Now this may be bullet design dependent but it appears many bullets shoot better when they are jumped. That old jam them into the lands is quickly becoming an old wives tale.
Here is some of the of the articles that include the testing Litz and Marc Gordon did along with a recent podcast where Satterlee talks about super long freebores shooting better with high jumps
Bullet Jump & Seating Depth: Best Practices & Conventional Wisdom
With so many events canceled and stores closed, what a great time to do some reloading! Over the pa...Bullet Jump: Is Less Always Better?
About 2 years ago, Mark Gordon shared some preliminary research he’d conducted with the Applied Bal...More Bullet Jump Research!
This is the 4th article in a series on some new research on bullet jumps. Here is a recap of the pr...
It might behoove folks to read though and watch that video and see if its changes their view on some things.
You’re completely confusing things.
None of these videos or articles even remotely describe what you’re saying. Marc Gordon even says that you will get smaller groups without the long jumps.
His method is about getting the most consistent precision across PRS round counts.
Likely because we have never been able to actually measure many aspects of what is happening when you launch a bullet out of a tube. But that's changing with technology and we should be seeing some real science behind the process. Then things will get really interesting.
Question for you guys:
I took some time off from matches in the fall for coaching football. Started up again recently and saw a weird thing happen to my rifle.
In the summer before my hiatus my GT was running 105 hybrids with 4350 at around 2870 with 35.5 gr.
Now in the winter with the same load last weekend my chrono was clocking 2900 fps. I may need to trim brass, it’s been so long I can’t remember. Can long brass cause the higher speed due to higher pressure or is there something else I need to be looking at?
I took some time off from matches in the fall for coaching football. Started up again recently and saw a weird thing happen to my rifle.
In the summer before my hiatus my GT was running 105 hybrids with 4350 at around 2870 with 35.5 gr.
Now in the winter with the same load last weekend my chrono was clocking 2900 fps. I may need to trim brass, it’s been so long I can’t remember. Can long brass cause the higher speed due to higher pressure or is there something else I need to be looking at?
I doubt it’s a trim length. But have a few questions:
- How many rounds since last cleaning?
- Newly loaded ammo or was this ammo you loaded and left on shelf? If left on shelf, was it inside house or some sort of climate controlled area?
- Same jug/lot of powder? If yes, where/how was it stored?
Fair questions,
-Recently cleaned the chamber and a few patches down the barrel but nothing deep or intensive. Probably 100 rounds I guess.
-Newly loaded the night before
-same lot/jug of powder, stored in a cool dry place in my insulated garage
I got nothing then. At least no immediate and obvious answer.
Except depend on the sample size and what not, could be on either end of your ES area on chrono each time.
In typically don’t worry about fairly small fluctuations like this unless they are erratic. So many things that could be contributing.
From a FB post by George Gardner:
Latest 6mm GT News
Adopted by SAAMI Jan 23 2022
Hornady is well into production of the 109 gr ELD ammo, I’ve tested 3 different pre production samples and found a great load that produces silly accuracy out of several test rifles. Target Speed is 2900 out of a 26” barrel. This will likely be 2880-2920 depending on your rifle and type of barrel. The power is temp stable and burned very clean. I cannot tell everyone what it is as it’s a powder that is not sold in canister line. But Burn Rate seems to between Varget and H4350. SD average was under 10 for an average across 4 different rifles and several 5 shot groups per rifle. I am super happy with the results.
I did test it with a couple Gas Guns and it ran well with very minor pressure signs. Didnt note any primer issues or and major Edjector marks.
Production should be completed in Feb with ammo and bullets shipping prior to March 1st.
Latest 6mm GT News
Adopted by SAAMI Jan 23 2022
Hornady is well into production of the 109 gr ELD ammo, I’ve tested 3 different pre production samples and found a great load that produces silly accuracy out of several test rifles. Target Speed is 2900 out of a 26” barrel. This will likely be 2880-2920 depending on your rifle and type of barrel. The power is temp stable and burned very clean. I cannot tell everyone what it is as it’s a powder that is not sold in canister line. But Burn Rate seems to between Varget and H4350. SD average was under 10 for an average across 4 different rifles and several 5 shot groups per rifle. I am super happy with the results.
I did test it with a couple Gas Guns and it ran well with very minor pressure signs. Didnt note any primer issues or and major Edjector marks.
Production should be completed in Feb with ammo and bullets shipping prior to March 1st.
True, Ill go out and shoot it again this week. I guess if its consistent then it probably doesn't matter much. Still groups well. If I wanted to adjust the speed and back it back down to 2880, how much H4350 should I anticipate taking out from my current 35.5? I guess I am asking how many grains of 4350 change the speed 20 fps or so
And now back to your regularly scheduled programming of load development....
GA Precision PPR rifle 6gt 260 rounds fired. I have been working loads with several powders, primers, and bullets. Here are best results in my rifle. Please note only testing combustion, not tuning. Seating depth with group analysis will be next. Here I focused on speed, ES, and SD.
112MB, alpha brass, Cci450, Coal 2.540, Rl16
36.8 2885fps 13Es 6Sd 5rds fired
37.0 2884fps 5Es 2Sd 5rds
37.2 2910fps 6Es 2Sd 5rds
37.4 2919fps 9Es 3Sd 4rds
105Berger Hy, horn brass, S&B primer, Coal 2.560, IMR4166
34.0 2979fps 21Es 8Sd 5rds
34.5 3018fps 17Es 7Sd 5rds *no obvious signs of pressure*
--same as above but Cci450 primers--
33.5 2942fps 11Es 4Sd 5rds
34.0 2972fps 26Es 9Sd 5rds
105 hornady Bthp match, horn brass, S&B primers, Coal 2.500, IMR4166
32.4 2865fps 6Es 3Sd 5rds
*group was one hole .3 or less
All brass was on second firing and first resizing. Shoulder bumped .002 with RCBS FL .266neck bushing. Trim 1.720.
GA Precision PPR rifle 6gt 260 rounds fired. I have been working loads with several powders, primers, and bullets. Here are best results in my rifle. Please note only testing combustion, not tuning. Seating depth with group analysis will be next. Here I focused on speed, ES, and SD.
112MB, alpha brass, Cci450, Coal 2.540, Rl16
36.8 2885fps 13Es 6Sd 5rds fired
37.0 2884fps 5Es 2Sd 5rds
37.2 2910fps 6Es 2Sd 5rds
37.4 2919fps 9Es 3Sd 4rds
105Berger Hy, horn brass, S&B primer, Coal 2.560, IMR4166
34.0 2979fps 21Es 8Sd 5rds
34.5 3018fps 17Es 7Sd 5rds *no obvious signs of pressure*
--same as above but Cci450 primers--
33.5 2942fps 11Es 4Sd 5rds
34.0 2972fps 26Es 9Sd 5rds
105 hornady Bthp match, horn brass, S&B primers, Coal 2.500, IMR4166
32.4 2865fps 6Es 3Sd 5rds
*group was one hole .3 or less
All brass was on second firing and first resizing. Shoulder bumped .002 with RCBS FL .266neck bushing. Trim 1.720.
I know this no surprise to many but in this clambering I have found 4166 to work as well if not better than Varget. Just my experience in this specific case.
It was load development relevant as this means we’ll be getting published load data soon. Should be in the Hornady app in the 3 months.
Has anyone ran the Berger 108 elite hunter in a GT? It’s still a high bc Berger hybrid so I figured I’d run them until I can accumulate some more 109 hybrids. Going to run either varget or h4350. Thanks.
I have run 1500 of them through my GT along with the 108 match. They run pretty much exactly the same. Same accuracy, same DOPE to 1400 yards, same charge weight, same CBTO.
I see a lot of references to the Berger Hybrids, but haven’t been able to find them. I did pick up some 105 VLDs. Has anyone had luck with them? Any tricks or things to watch for loading these?
I am no expert in reloading by I try to read alot and listen to those who shoot the best. They already have it figured out so no reason to try and reinvent the wheel, or at least that's the thought process.
Now this may be bullet design dependent but it appears many bullets shoot better when they are jumped. That old jam them into the lands is quickly becoming an old wives tale.
Here is some of the of the articles that include the testing Litz and Marc Gordon did along with a recent podcast where Satterlee talks about super long freebores shooting better with high jumps
Bullet Jump & Seating Depth: Best Practices & Conventional Wisdom
With so many events canceled and stores closed, what a great time to do some reloading! Over the pa...Bullet Jump: Is Less Always Better?
About 2 years ago, Mark Gordon shared some preliminary research he’d conducted with the Applied Bal...More Bullet Jump Research!
This is the 4th article in a series on some new research on bullet jumps. Here is a recap of the pr...
It might behoove folks to read though and watch that video and see if its changes their view on some things.
Agreed.
I don’t know when GAP will get more GT brass but I did speak with Alpha in December and they told me they are doing “a very large run” of GT brass in early 2022.
I've had some weirdness with 112gr Match Burners and 6.5 StaBall lately.
I've chrono'd this load at 2,948 fps @ 80 deg and 2,935 fps @ 35 deg. Then I went a week ago and groups opened up and I was at 3,011 fps @ 55 deg.... I did change a few variables, I was using a new batch of 112gr and I was using a new batch of GAP cases, which were within a tenth or two of my older brass in measured case capacity after firing. Hard to figure what would cause that kind of bump, maybe smaller starting case capacity on new brass? I don't think I've ever seen a difference that significant though.
I'm curious what mags folks are having good luck with, my MDT works well with under 8 rounds loads loaded, but I get nose dive with more than that, even after adjusting feed lips.
I've chrono'd this load at 2,948 fps @ 80 deg and 2,935 fps @ 35 deg. Then I went a week ago and groups opened up and I was at 3,011 fps @ 55 deg.... I did change a few variables, I was using a new batch of 112gr and I was using a new batch of GAP cases, which were within a tenth or two of my older brass in measured case capacity after firing. Hard to figure what would cause that kind of bump, maybe smaller starting case capacity on new brass? I don't think I've ever seen a difference that significant though.
I'm curious what mags folks are having good luck with, my MDT works well with under 8 rounds loads loaded, but I get nose dive with more than that, even after adjusting feed lips.
@Gtscotty
I wouldn’t call that weirdness. You changed two variables. Back it down and build your charge back up to where it shoots good again. It should be pretty close in speed to what you had before. Provided you fall between the 35° and 80° you tested at before. It may not be the exact same speed as the cases and bullet has changed, but it should be ball park.
If you haven’t cleaned your barrel in a long time that could be a contributing factor as will. If you clean it give it ten rounds or so to start settling in before doing any load development.
I wouldn’t call that weirdness. You changed two variables. Back it down and build your charge back up to where it shoots good again. It should be pretty close in speed to what you had before. Provided you fall between the 35° and 80° you tested at before. It may not be the exact same speed as the cases and bullet has changed, but it should be ball park.
If you haven’t cleaned your barrel in a long time that could be a contributing factor as will. If you clean it give it ten rounds or so to start settling in before doing any load development.
Hmm, I call it weirdness because I've been loading a bunch of different chamberings for a while now, and I've never seen a bullet lot change jack pressures like that. For reference, that's the same velocity that 40.3gr (0.8gr more) of StaBall gave me at 80 deg (25 deg warmer). I've used two other lots of this bullet, and there was no noticeable difference in velocities between them.
A new lot of cases with significantly lower capacity could definitely jump pressures, but I checked the water capacity on these when I got back, and trimmed the same they *may* be 0.1gr less... not nearly enough difference to explain what I measured. That's why it's weird to me, the only other thing I can think of is maybe the new cases are significantly undersized until they get blown out in the first firing, and are changing the powder burn characteristics quite a bit? Still seems like a lot though.
This barrel only has 300-400 rounds on it, and has honestly been surprisingly picky, but I guess I can't rule out a ring. I've cleaned pretty regularly, but I should probably break out the bore scope and check things out.
I did try some RL16 (my all around favorite medium rifle powder if I had to pick one) with the 112gr. Groups weren't impressive at the lower loads, but started to come together at 36.7gr and 37gr. More work to be done in that area, but here were the (only one shot) velocities:
112gr MB, Hornady Gap cases, 450s, 60 thou off the lands. 23" PVA prefit.
RL16
35.8gr - 2,849 fps
36.1gr - 2,887 fps
36.4gr - 2,874 fps
36.7gr - 2,915 fps
37gr - 2,901 fps
I Chrono'd 37gr of RL16 in the old cases with an older lot of bullets on the same 35deg trip mentioned above at 2,895 fps. So same components shift as with the StaBall load above didn't really change much, certainly not a 70fps change.
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Something has changed enough to give you a lot more pressure, that much is known. The hard part will be running it down.
Was load development done on a new barrel or after a couple hundred rounds? Maybe the barrel has sped up?
I've not shot StaBall, but I have gone through a few jugs of RL16. I learned the hard way with it to stay on top of cleaning or pay the price with carbon rings. I've heard StaBall is dirty, but I don't know about carbon rings. Maybe your bore scope will have some answers for you?
Was load development done on a new barrel or after a couple hundred rounds? Maybe the barrel has sped up?
I've not shot StaBall, but I have gone through a few jugs of RL16. I learned the hard way with it to stay on top of cleaning or pay the price with carbon rings. I've heard StaBall is dirty, but I don't know about carbon rings. Maybe your bore scope will have some answers for you?
I'm running 5, 10 and 12 round MDT mags with my GT and I don't have any issues. I'm using an MDT ACC and a ARC Nucleous action. I have shot 109s and 105s mostly. I tested some 112s this summer but didn't get the results I was looking for and went back to Bergers. I wouldn't think 3 or 7 grains would make a difference on the way the mag feeds? Have you ran lighter bullets?
One hole with 109, 108, and 112. Just different seating depths. 0.050 for 112 & 108. 0.060 109’s. I use the MDT polymags. No issues except the first round am the do have the mag extension. Just takes a bit more umph. Like anything else can’t load mag against berricade
I've never been able to get MDT mags to run in my GT's.
AI or ARC seems to run well for me.
AI or ARC seems to run well for me.
It’s all in adjusting and tuning the feed lips. I’ve spent hours getting them just right, fighting down my notes, and repairing them after I’ve squished them.
If my options are spending hours playing with feed lips, or buy a different mag that works out of the box, I'm going to buy a different mag.
To each their own, I guess.
I would say development was done over a couple hundred rounds, lol. The 80 deg velocities were early on, but the others were all recent. Searching for a consistent load with this rig has been more of a struggle than I'm used to, but I've primarily been using the 112gr with a couple unimpressive sessions of 108gr ELD sprinkled in, so maybe that's the problem... I saw that Proof is going to start making 6GT Origin prefits, so maybe I'll just pick up one of those when they come out and see if that clears things up.
I need to find some Bergers, I heard there was supposed to be a batch of 105gr Hybrids shipping soon, but I haven't seen anything. I don't think the bullet weight is having any effect, the nose dive is a mag issue, and I thought messing with the feed lips would fix it, but it didn't, maybev I'm just not there yet. I have a Magpul mag that never has nose dive, but this rifle over runs the case head pretty often with that mag, weird thing is that mag also caused the same malfunction in my old RPR in 6.5.
