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Re: Barrel life and powder burn rate [Re: Mkopmani] #15000823 06/26/20
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I don’t believe so. I haven’t used a pile of it but it’s much like the old H870 but cleaner burning once you’re at pressure.


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Re: Barrel life and powder burn rate [Re: Mkopmani] #15001914 06/26/20
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Ive shot a 264 for several years. Imr7828 is your friend. Something around 66.5g with a 130 in win brass cci 250 should be about 3350 fps.

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Re: Barrel life and powder burn rate [Re: Burleyboy] #15002439 06/27/20
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That's interesting.

Hodgdon lists 60.1 grains of 7828 as maximum with the 130-grain Nosler AccuBond, for 3053 fps from the now-standard SAAMI 24" test barrel at 63,200 PSI. That's using Winchester brass and the Winchester LR Magnum primer. A 26" barrel would probably get 3100 or a little more.


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Re: Barrel life and powder burn rate [Re: Mule Deer] #15002463 06/27/20
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Originally Posted by Mule Deer
That's interesting.

Hodgdon lists 60.1 grains of 7828 as maximum with the 130-grain Nosler AccuBond, for 3053 fps from the now-standard SAAMI 24" test barrel at 63,200 PSI. That's using Winchester brass and the Winchester LR Magnum primer. A 26" barrel would probably get 3100 or a little more.


John, weren’t you the one that’s used Magnum and 140’s for a few 264’s and said 3150-3200 wasn’t any big trick? I could’ve sworn that’s where I got the idea.


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Re: Barrel life and powder burn rate [Re: Mule Deer] #15009349 06/29/20
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Originally Posted by Mule Deer
Originally Posted by Filaman
For one thing I never thought of 4350 as being fast. But I can see the OPs point. Fast powder has a fast pressure peak. Higher pressure=higher temp.


No, not nearly correct. The more powder burned, the higher the temperature--especially with double-based powders, though the temp difference isn't all that much compared to single-based powders.


Seems like there might be more data buried in the lab bomb test data (depending on what they collect).
It's just thermodynamics and the ideal gas law PV=nRT

It's really about heat calories released from the powder(which is tied to powder burned) and how much energy is in the powder. That might be something captured in the burn rate bomb tests...

The other factor is heat transmission. Different alloys/grades transmit heat differently.
Fast transmission is good because it means the barrel cools quickly...

You might have heat sensitive hands too...


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Re: Barrel life and powder burn rate [Re: Mkopmani] #15014672 07/01/20
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30 years ago Bart Bobbitt came up with formula for barrel life.

https://yarchive.net/gun/barrel/bar...l.,3000%20rounds%20of%20good%20accuracy.

But when a top level competitor thinks a barrel is shot, and when a putz like me thinks a barrel is shot, are too different amounts of erosion.


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Re: Barrel life and powder burn rate [Re: keith] #15014704 07/01/20
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Originally Posted by keith
There is one heck of a difference in the Heat Index between various powders. This is evidenced by how difficult some are to clean as the carbon gets cooked on to a much higher degree than others.

I tried to copy and post the Heat Index chart where they give the Relative Heat Index of all powders listed by the coolest to the hottest.



keith, that makes a lot of sense. It doesn't look like your chart came through, but do you have a link to it online? I'd like to take a look.

Re: Barrel life and powder burn rate [Re: Mkopmani] #15014972 07/02/20
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I've shot 3 shot groups of H1000 and N570 through my 30-28 Nosler at basically the same rate of fire and I can tell you for sure the barrel is hotter to the touch after shooting N570. Personally the more I use H1000 in magnums the more of a fan I am it's very temp stable also.

Re: Barrel life and powder burn rate [Re: OldmanoftheSea] #15037211 07/10/20
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Originally Posted by OldmanoftheSea
Seems like there might be more data buried in the lab bomb test data (depending on what they collect).
It's just thermodynamics and the ideal gas law PV=nRT

It's really about heat calories released from the powder(which is tied to powder burned) and how much energy is in the powder. That might be something captured in the burn rate bomb tests...

The other factor is heat transmission. Different alloys/grades transmit heat differently.
Fast transmission is good because it means the barrel cools quickly...

You might have heat sensitive hands too...
That is it in a nutshell. It's all about heat. Not just heat released, but heat absorbed by the barrel throat. More powder --> more heat. The amount of powder obviously effects the amount of heat, but also the heat content of the powder has an effect. Joe Hendricks has provided a great illustration of this with his use of H1000 in the .243 Winchester. You can see the heat content for many powders in the Excel file found at https://www.accurateshooter.com/technical-articles/excel-formula-predicts-useful-barrel-life/ Those numbers are taken from Quickload.

A factor many overlook is the bullet. Again, heat absorption is key. The heavier the bullet the longer it takes to engrave in the throat. The longer this dwell time, the more heat is absorbed. That is why loads that have more powder but feature a lighter bullet will usually wear out the barrel at a slower rate. And it's the key to Danzac and Moly. These bullet lubricants allow the bullet to engrave faster resulting in less dwell time in the throat and less heat being absorbed by the barrel.


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Re: Barrel life and powder burn rate [Re: sherm_61] #15037224 07/10/20
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Originally Posted by sherm_61
I've shot 3 shot groups of H1000 and N570 through my 30-28 Nosler at basically the same rate of fire and I can tell you for sure the barrel is hotter to the touch after shooting N570. Personally the more I use H1000 in magnums the more of a fan I am it's very temp stable also.
Makes sense. N570 has a heat content of 4000 kJ/kg and H1000 has a heat content of 3630 kJ/kg. You'll get better barrel life from H1000.


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Re: Barrel life and powder burn rate [Re: Mkopmani] #15039101 07/10/20
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Finally was able to get out to the range and try the Ramshot in 120 and 130gr Hornady ELDs. The 1:9 twist seems to favor 120's over 130's and this was no different. The Ramshot is WAY cooler than RL33; I shot both allowing cool time between shots. On a cold barrel, RL33 makes the barrel hot to touch. Can shoot 3 RDA of Ramshot before it's this hot. Group size with the Ramshot 120's was in the 0.75" for 4 shots. I'll have to work more before judgement, but it's definitely cooler than RL33. Had great results with RL19 & 120gr, 3 shots touching for 1 tear, 1 flier 3/8" away.

Re: Barrel life and powder burn rate [Re: Mkopmani] #15062771 07/19/20
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"3 shots touching for 1 tear, 1 flier 3/8" away." Wish my flyers were only 3/8" away! smile

Re: Barrel life and powder burn rate [Re: Mkopmani] #15063723 07/19/20
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I will say that when you work up reduced loads using fast burning powders, especially pistol powders, that as the charge goes down, the heat goes down. It isn't a matter of pressure, because I've got a 17 FB load using TiteGroup that runs what seems to be very close to full pressure, and I can fire 3 times the rounds that I can with "standard" powders before the barrel gets hot.

I've also noticed that single base powders in full charges generate less heat than those using double base powders. And that cases full of powder warm up a barrel faster than cases with less fill. Seems like less powder would equal less barrel erosion, since erosion is a product of heat, but I have never been able to discern how much it matters. Not enough, I think, moving between 90% case fill and 105% case fill.


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Re: Barrel life and powder burn rate [Re: Tyrone] #15080865 07/25/20
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Originally Posted by Tyrone
Originally Posted by OldmanoftheSea
Seems like there might be more data buried in the lab bomb test data (depending on what they collect).
It's just thermodynamics and the ideal gas law PV=nRT

It's really about heat calories released from the powder(which is tied to powder burned) and how much energy is in the powder. That might be something captured in the burn rate bomb tests...

The other factor is heat transmission. Different alloys/grades transmit heat differently.
Fast transmission is good because it means the barrel cools quickly...

You might have heat sensitive hands too...
That is it in a nutshell. It's all about heat. Not just heat released, but heat absorbed by the barrel throat. More powder --> more heat. The amount of powder obviously effects the amount of heat, but also the heat content of the powder has an effect. Joe Hendricks has provided a great illustration of this with his use of H1000 in the .243 Winchester. You can see the heat content for many powders in the Excel file found at https://www.accurateshooter.com/technical-articles/excel-formula-predicts-useful-barrel-life/ Those numbers are taken from Quickload.

A factor many overlook is the bullet. Again, heat absorption is key. The heavier the bullet the longer it takes to engrave in the throat. The longer this dwell time, the more heat is absorbed. That is why loads that have more powder but feature a lighter bullet will usually wear out the barrel at a slower rate. And it's the key to Danzac and Moly. These bullet lubricants allow the bullet to engrave faster resulting in less dwell time in the throat and less heat being absorbed by the barrel.


Didn't see your response Tyrone until today...
Good point on bullet weight. But don't forget monolith bullets. They will have a slightly different absorption rate..


-OMotS



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Re: Barrel life and powder burn rate [Re: OldmanoftheSea] #15085076 07/27/20
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Originally Posted by OldmanoftheSea
Good point on bullet weight. But don't forget monolith bullets. They will have a slightly different absorption rate..

I don't use monos. I imagine they are harder on barrels?

Steel jackets are harder on barrels. They are harder to engrave and they don't upset as well as copper jackets, allowing for more gas cutting.


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Re: Barrel life and powder burn rate [Re: Mkopmani] #15086502 07/27/20
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I was thinking of Copper monoliths like the GMX.
But solid copper should be "stiffer" th a copper around a lead core...
But their relative specific heat capacities. I would have to look those up...

Yeesh,
Yeah a steal jacket could be tough on the lands...


-OMotS



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Re: Barrel life and powder burn rate [Re: Mkopmani] #15086616 07/27/20
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About "dwell" time, if you seat your bullets deeper when they hit the rifling they will be going faster so dwell time will be reduced. Is it possible seating bullets deeper will help barrel life?

Re: Barrel life and powder burn rate [Re: rickt300] #15087074 07/27/20
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I think at least based on the experience so far with my 264 WM, it looks like total powder burned is the first factor, then the second is burn rate of the powder, or time for the heat to conduct into the barrel. These are probably not unique, and they are intuitive, but I was thinking that maybe peak temp of a fast burning powder was more of a factor than it appears to be. Total heat and time for conduction appear to be the drivers that I see.

There is a significant difference in heat between Ramshot and RL33, but RL33 is still slower, and I'm wondering if at lower pressure the RL33 consists that much slower than Ramshot. I'd still like to try Retumbo but can't find any around here for sale or through Midway.

Re: Barrel life and powder burn rate [Re: Mkopmani] #15101447 08/01/20
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Originally Posted by Mkopmani
I have a 264 Win Mag Sense to and am developing loads for accuracy. As the 264 has ample case capacity and I generally like to have 90%+ fill, this would favor the slower powders. That said, I've tried some RL33 and noticed the heavy barrel is not after 1 firing on a cold barrel. Closely similar velocities with faster powders seem to put less heat in the barrel.

Q's: Assuming I find an accurate load with faster powders (IMR4350 is not bad), will the barrel life be better off with the faster powders or slower powder? I had thought that peak temp would be lower and favor the slow powder, but I'm having second thoughts on that theory.


The first gunsmith I used for a re-barrel had a dislike for any powders slower than 4350. He believed that slower powders eroded throats faster than 4350 and challenged whether any real benefit existed from that opinion. That was several decades ago now and I for one, cannot prove him wrong.


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Re: Barrel life and powder burn rate [Re: Mkopmani] #15102626 08/02/20
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RL-33 is different than many powders. It has a longer burning curve like RL-17. Perhaps that is where some of the extra heat is coming from.

From my documents file:

RL-33 is only the second of a line of unique powders offered by Alliant. Borrowed this line from an ad: "New Reloder 33 Delivers More Speed in Big Magnums Now Alliant is introducing a new powder, Reloder 33, that uses the same kernel-impregnation technology first pioneered in Reloder 17. Alliant Reloder 33 is a new powder created by Rheinmetall Nitrochemie.

Be careful trying a bunch of powders and bullets. It won't be long before the barrel is shot out. I know I did it to a 257 weatherby. Learned plenty and the second barrel only shoots one bullet and one powder. Incidentally the powder is RL-33.

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