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6mm GT

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Forming the false shoulder and fireforming. Unless you're using Norma Dasher brass that seems to be the way most people load it: http://forum.accurateshooter.com/threads/6-dasher-fire-forming-false-shoulder-step-by-step.3918893/

I'm just saying it's extra steps I personally don't want to do. Are you guys not forming the false shoulder or are you using Norma brass?

I bought Lapua 6BR hydroformed into Dasher brass. After doing the math paying for hydroforming was a little less than cost of the bullet+primer+powder I would've used for one round of fireforming. The hydroformed brass was 100% load and shoot, and was consistent enough that I used it in a couple of matches.
 
There are hardly any shooters using the false shoulder methods anymore because it yields not advantages. Look at the BR guys. It’s either load and shoot or hydroform. Stick with the Lapua.
 
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Theres are so many variables it's hard to say on barrel life for a caliber. I hate to say this but I went the route of 6 comp match. Very small following but I have been very happy on barrel life
 
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I jammed all my Dasher fireform loads. It's really not any different than forming BRA. Set seating depth, load in gun, pull trigger

BRA is a bit more forgiving when fireforming by all reports.

You don't need to jam bullets or create false shoulders with BRA. Because you are only changing the shoulder angle and not actually changing the shoulder position the process is easier on the brass.

The first loading of 6BRA is essentially 6BR, then after that you get the BRA velocities. No split necks, and the accuracy is incredible with the FF loads. You can shoot matches with 6BRA FF loads.
 
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You know Dasher and Dancer and Prancer and Vixen
Comet and Cupid and Donner and Blitzen
But do you recall
The most famous reindeer of all?
Rudolph the Red-Nosed Reindeer
Had a very shiny nose
And if you ever saw it
You would even say it glows
All of the other reindeer
Used to laugh and call him names
They never let poor Rudolph
Join in any reindeer games
Then one foggy Christmas Eve
Santa came to say
"Rudolph, with your nose so bright
Won't you guide my sleigh tonight?"
Then how the reindeer loved him
As they shouted out with glee
"Rudolph the Red-Nosed Reindeer
You'll go down in history"
Rudolph the Red-Nosed Reindeer
Had a very shiny nose
And if you ever saw it
You would even say it glows
 
Forming the false shoulder and fireforming. Unless you're using Norma Dasher brass that seems to be the way most people load it: http://forum.accurateshooter.com/threads/6-dasher-fire-forming-false-shoulder-step-by-step.3918893/

I'm just saying it's extra steps I personally don't want to do. Are you guys not forming the false shoulder or are you using Norma brass?
how long does an extra step take? after fireforming you just load and shoot it 10-20 times. Unless you are going through thousands of rounds of brass prep every year with a Dasher...it's no big deal.
 
As far as die sets go for the 6GT, GAP is offering currently a non bushing Hornady set and a new RCBS match master bushing style die set.

Which one of these would be recommended? Plus and minus of going with either set?
 
Their are some more advantages of the GT over some of the others. Here are some of the reasons for its development

No feeding issues out of a non modified mag (yes some don’t have issues with dasher, but lots do especially from an aw/ax double stack)

The ability to run varget over h4350. The size of both the creed and XC lend to h4350 burn rate and fill capacity being better. Varget is just PFM. One of the reasons dasher shoots so well. And 6.5x47.

35 deg shoulder and case design (hardness and overall wall thickness). A case is not a case. Internals matter.

Available brass without having to fire form. GAP is also going to try and start this out right without 5000 different readers from guys who “know best”. This should help keep everything where it needs to be.

Now the real question is how will the market react if there is quality GT and dasher brass available.
 
Theres are so many variables it's hard to say on barrel life for a caliber. I hate to say this but I went the route of 6 comp match. Very small following but I have been very happy on barrel life


How's that going? Of the barrels I saw torched in 6 comp, they ranged from 1200-1800 rounds. 1800 had been making it stretch out for a couple hundred rounds, too.

Listen to the right people and it's "3400fps and 3000 rounds with a 105"... I've never seen either of those.
 
How's that going? Of the barrels I saw torched in 6 comp, they ranged from 1200-1800 rounds. 1800 had been making it stretch out for a couple hundred rounds, too.

Listen to the right people and it's "3400fps and 3000 rounds with a 105"... I've never seen either of those.
I run a .243AI shooting H1000 with 105 and 115 bullets. Pretty much the same concept as the 6 comp match. I don't push it hard. 3170 and 3050 respectively. The first barrel was done at 2500 rounds. I tried to milk more and pulled it at 2800 after shooting really shitty at a match and taking it to the range to find it wouldn't hold vertical at 800 yds. The second barrel is at 1400 rounds. It is still shooting sub half moa, but the throat has advanced a bit and I had to chase it and add powder to get the velocity back at around 900 rounds. For the amount of powder it takes to get that performance I'm thinking there has to be better alternatives. I'm going to burn through two more barrels and then evaluate if I want to go a different route. Then I'll have a better idea of what the average barrel life is, so I can compare it to whatever I try next. I think to get 3400 fps out of it a guy would have to run a 30" barrel and a shitload of pressure. In my opinion that is likely to make the barrel life very poor.
 
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Alpha Munitions has a waitlist for the new Redding 6GT Type S Match Bushing dies and GAP has the RCBS 6GT Matchmaster dies. The Redding dies are going to go for $289 while RCBS is only $163.54. I'm trying to decide between Redding or RCBS.
 
Ya little over $300 after shipping plus you have to find a bushing. That's another $20 to 30 + shipping. Would have close to $340 in just the dies. Or I could try the RCBS for $164. GAP wants $18 to ship to me so $182. ( was pulling the trigger on these until I seen the $18 shipping). Still leaves me $158 for brass. I'm thinking brass will be about $1 to $1.10 each so 100 will be $110. Going with the RCBS I will have Dies and 100rd of brass and an extra $58 in my pocket for another 100 rounds of brass.
As you can tell I'm trying to justify buying the RCBS but all this math is making me wonder if I really need another caliber at all! Haha!
 
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Ya little over $300 after shipping plus you have to find a bushing. That's another $20 to 30 + shipping. Would have close to $340 in just the dies. Or I could try the RCBS for $164. GAP wants $18 to ship to me so $182. ( was pulling the trigger on these until I seen the $18 shipping). Still leaves me $158 for brass. I'm thinking brass will be about $1 to $1.10 each so 100 will be $110. Going with the RCBS I will have Dies and 100rd of brass and an extra $58 in my pocket for another 100 rounds of brass.
As you can tell I'm trying to justify buying the RCBS but all this math is making me wonder if I really need another caliber at all! Haha!
I went with the RCBS dies. Same reasoning it's a little cheaper so I can use that extra money for brass.
 
Considering the fact that you're not the only engineer involved in the discussion and that you completely discount the ideal gas law, I'm going to go ahead and "assure you" that what you're thinking may not be as true as you think.

A pressure spike of 60,000 PSI (max SAAMI average pressure) will cause a fair amount of heat. How much heat?

Case capacity of a 6.5 Creedmoor is approximately 52.5 grains of water, or 3.4 grams meaning the volume is approximately 3.4 milliliters. Approximately 50% of this volume will be taken up by solids (the gunpowder and the bullet, taking into account packing density of gunpowders is less than 100%) meaning we get a gaseous volume of ~1.7 milliliters.

Initial Condition:
101,325 * 0.0017 = n * R * 273.15
n = (101,325 * 0.0034)/(R * 273.15)

Solving for n we get that the original amount of gas in the chamber is approximately 0.07585 moles.

Gunpowder is approximately 75% Potassium Nitrate (KNO3), 15% Charcoal (C), and 10% Sulfur (S). The approximate chemical formula for the burning of gunpowder is as follows:

10 KNO3 + 8 C + 3 S -> 2 K2CO3 + 3 K2SO4 + 6 CO2 + 5 N2, of which Carbon Dioxide and Nitrogen are gasses while Potassium Carbonate and Potassium Sulfate are solids. By a percentage of the weight of the original gunpowder, perfect combustion will create 21.96% CO2, 11.65% N2, and 66.39% solids.

Let's use a standard 6.5 Creedmoor load of 40 grains of powder, which with perfect combustion would create approximately 8.784 grains of Carbon Dioxide and 4.66 grains of Nitrogen gas. This translates to 0.5692 grams of CO2 and 0.302 grams of N2, or 0.0129 moles and 0.0108 moles of the two gasses respectively combining for a total of .0237 moles of gas created by perfect combustion of 40 grains of gunpowder.

This means that the new amount of gas in the chamber after combustion (during the pressure spike) is 0.09955 moles. We also have a new volume since the gunpowder isn't there anymore, meaning the volume is approximately the 3.4 milliliter case capacity. The pressure of 60,000 PSI translates to approximately 413,685,420 pascal.

Post Combustion Condition (60,000 PSI):
413,685,420 * .0034 = 0.09955 * 8.3145 * T
T = (413,685,420 * 0.0034)/(0.09955 * 8.3145)

Our final temperature after the combustion, ignoring the heat from combustion itself, is approximately 1,700,000 degrees Kelvin (1.69931 x 10^6). This translates to 3,059,540 degrees Fahrenheit.

The temperatures realistically experienced in the chamber will be a significant amount lower because combustion is not perfect, nor is it instantaneous, and the volume is constantly expanding - this is an idealized spherical cow in a vacuum type calculation. This is demonstrated by the graphs posted already above.

Do you honestly believe though, in the face of the hard math and the data provided, that there is still no correlation between the temperatures and the pressures experienced within the chamber and throat of the barrel?

Mind. Blown.
 
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How's that going? Of the barrels I saw torched in 6 comp, they ranged from 1200-1800 rounds. 1800 had been making it stretch out for a couple hundred rounds, too.

Listen to the right people and it's "3400fps and 3000 rounds with a 105"... I've never seen either of those.

3050 Fps
H1000
More than 2500
 
If you guys didn't see it, Alpha has been taking pre-orders and is now taking regular orders for brass, $115 per hundred.
 
View attachment 7011798

GAP Needs to reinvent the wheel every few years to keep the retards that have to buy a whole new $5k rifle every time there's a new caliber on the market, salivating.

Nevermind it does nothing ballistically different than current cartridge offerings. I'm sure the barrel life will be 6k rounds too! I'll stick with my 6x47.
Re: steel barrel for mpr.
Want to keep it zeroed ready to go with the carbon barrel for hunting.



The funny part is this is so trueeeeee

Scott