Powder burn rates and barrel length

[360hunt]

So I have a new 30-06 carbine 18.5" to load for.
All data in my manuals are for longer barrels 24"-26" . I would think I'm going to have alot of unburned powder in the shorter barrel.
Would you use faster powders than recommended to compensate for this?

Thanks

[Dean2]

All the powder is burned in far less than 18.5". The issue with the shorter barrel is you have less length where the expanding gases are enclosed and acting on the bullet, that is why a faster powder is recommended in shorter barrels. It builds pressure faster and hits peak pressure sooner allowing for more velocity out of the shorter barrel. It has nothing to do with being able to burn all the powder, that happens with the fastest or slowest. I would stay with recommended powders but use the fastest powder that still produces top velocities with the desired bullet weight. Hope this helps.

For example, with a 150 grain bullet I would pick Benchmark over 4350.

[catnthehat]

Originally Posted by 360hunt

So I have a new 30-06 carbine 18.5" to load for.
All data in my manuals are for longer barrels 24"-26" . I would think I'm going to have alot of unburned powder in the shorter barrel.
Would you use faster powders than recommended to compensate for this?

Thanks

Don’t Screw around with anything but load book data!
The only difference you will see between the 24” and 18.5” barrels is some velocity , that’s it the pressures will be the same as will the powder burn with the same powder but a longer barrel
You will be fine going with published load data .
Cat

[Nyksta]

A faster burning powder and a slower burning powder both will lose about the same velocity as the barrel is shortened to 18.5". Use the powder with the highest velocity in the book for your bullet weight, and if you dont like that powder, try the next fastest.

[huntinstuff]

I experimented with this

I had a 22” barrel on a Sako 3006

I had it cut/recrowned three times to see if it affected accuracy

I got nervous at 20 inches and stopped lol

Made the rifle lighter and accuracy was unaffected.

I was using 180G Nosler Partition PPT with 57g of RL 22 and federal magnum primers.

[prarie_boy1]

Originally Posted by huntinstuff

I experimented with this

I had a 22” barrel on a Sako 3006

I had it cut/recrowned three times to see if it affected accuracy

I got nervous at 20 inches and stopped lol

Made the rifle lighter and accuracy was unaffected.

I was using 180G Nosler Partition PPT with 57g of RL 22 and federal magnum primers.

Did you run any loads over the chrony? I’d be curious to see the diff in velocity as the barrel was shortened. I had a .30-06 re barrelled about 6 years ago and decided on 22” finished length really didn't notice much of a velocity diff from the 24” factory barrel it had previously and the rifle feels better in the hands with the 22” barrel of a slightly heavier contour.

[Pathfinder76]

Originally Posted by huntinstuff

I experimented with this

I had a 22” barrel on a Sako 3006

I had it cut/recrowned three times to see if it affected accuracy

I got nervous at 20 inches and stopped lol

Made the rifle lighter and accuracy was unaffected.

I was using 180G Nosler Partition PPT with 57g of RL 22 and federal magnum primers.

Why would accuracy have been affected?

[360hunt]

Originally Posted by Dean2

All the powder is burned in far less than 18.5". The issue with the shorter barrel is you have less length where the expanding gases are enclosed and acting on the bullet, that is why a faster powder is recommended in shorter barrels. It builds pressure faster and hits peak pressure sooner allowing for more velocity out of the shorter barrel. It has nothing to do with being able to burn all the powder, that happens with the fastest or slowest. I would stay with recommended powders but use the fastest powder that still produces top velocities with the desired bullet weight. Hope this helps.

For example, with a 150 grain bullet I would pick Benchmark over 4350.

That does help
Thanks

[YYC338]

Originally Posted by chuck

Why would accuracy have been affected?

Possible change in barrel harmonics?

[huntinstuff]

Originally Posted by prarie_boy1

Did you run any loads over the chrony? I’d be curious to see the diff in velocity as the barrel was shortened. I had a .30-06 re barrelled about 6 years ago and decided on 22” finished length really didn't notice much of a velocity diff from the 24” factory barrel it had previously and the rifle feels better in the hands with the 22” barrel of a slightly heavier contour.

No chrony

I was only interested in accuracy

It was unaffected

[marxman]

Don’t change your powder, if loaded to the same pressure the slower powder will still give more velocity because there is more of it. A faster powder will theoretically give you less muzzle blast because the exit pressure is lower and there is less gas produced, loaded to the same peak pressure I mean

[Dean2]

Some of you guys need to seriously do some reading on powders, burn rates, pressure and the pressure curves different powders produce. If it was just a matter of running the slowest powder no one would bother producing data for so many load combinations for the same cartridge.

Here is about the least technical, simplest layman explanation I could find quickly. If you do some research there is a tremendous amount of very good, detailed information to be had but some of it does get very technical. Hope this helps.

https://www.outdoorhub.com/how-to/20...wder-charging/

[Nyksta]

Originally Posted by Dean2

Some of you guys need to seriously do some reading on powders, burn rates, pressure and the pressure curves different powders produce. If it was just a matter of running the slowest powder no one would bother producing data for so many load combinations for the same cartridge.

Here is about the least technical, simplest layman explanation I could find quickly. If you do some research there is a tremendous amount of very good, detailed information to be had but some of it does get very technical. Hope this helps.

https://www.outdoorhub.com/how-to/20...wder-charging/

Smokeless powder burn rate increases as pressure increases. There is a balance between too fast burn rate, and fizzling out way early, and the end result is a slower muzzle velocity. Too slow of a powder also doesn't work because the optimal pressure to promote optimal burn rate is never achieved either, and so the powder doesn't completely "activate" properly.

There is the optimal balance powder burn rate for each bullet weight in each cartridge because that powder at that charge with that resistance, achieves optimal pressure. The powder with the fastest muzzle velocity rating for a 24 inch barrel is also going to be optimal powder for barrel length that is reasonably similar length.

Jamming the bullet into the lands and increasing pressure, or having reduced loads will fail to match the book value load, and in situations where non-standard load practices are happening, then different powders will be better.

[KegRiver]

I also strongly advise against using any powder or charge not listed in reloading data.

Even the listed powders can lead to issues. I've had some experience with that.

As has been said, faster powders reach peak pressure sooner and all powders burn faster as pressure increases. And it IS a fine balance between the two.

I have a rifle that shows serious over-pressure with minimum listed loads with most of the powders recommended.

See there's a whole lot more at play then just muzzle flash or velocity.

In my books I find that many of the faster burning powders often list a far narrower range of recommended loads. That's a clue as to the danger you may put yourself in if you try a powder or charge not recommended for that cartridge.

The people who work up loads with untried powders do so with a lot of special equipment that the hand loader does not have access to, like extremely thick test chambers and explosion proof booths.

Even if you could find a powder that gives less muzzle blast, I'm betting that the improvement would be marginal. Not worth the risk by a long shot.

[KegRiver]

Anyone wishing to experiment with gun powder ought to see this video.


https://www.military.com/video/ammun.../1069432666001

[marxman]

Originally Posted by Dean2

Some of you guys need to seriously do some reading on powders, burn rates, pressure and the pressure curves different powders produce. If it was just a matter of running the slowest powder no one would bother producing data for so many load combinations for the same cartridge.

Here is about the least technical, simplest layman explanation I could find quickly. If you do some research there is a tremendous amount of very good, detailed information to be had but some of it does get very technical. Hope this helps.

https://www.outdoorhub.com/how-to/20...wder-charging/

Nobody said use the slowest powder. Use a powder that is suitable. I use 30 31 in my 24 inch 30 06 with 150 gr. Because it shoots fast enough and burns good and I believe it gives me a little less muzzle blast and recoil. I would certainly use it in an 18 inch barrel but if I wanted velocity I would still use more of a slower powder it would give more speed in either barrel. That article by the way has only a couple sentences on the subject and they are misleading.

[marxman]

Originally Posted by 360hunt

So I have a new 30-06 carbine 18.5" to load for.
All data in my manuals are for longer barrels 24"-26" . I would think I'm going to have alot of unburned powder in the shorter barrel.
Would you use faster powders than recommended to compensate for this?

Thanks

To answer your question no you don’t need a faster powder to burn it. If it doesn’t burn right it’s because of low pressure caused by a powder that is too slow or not enough of it. If it won’t reach high pressure in the first few inches it won’t finish burning no matter how long your barrel it will leave husks or yellowish Unburnt powder down your barrel

[Pioneer2]

About Elmer Keith when he was test firing .50 BMG's at the Ogdon plant.He said he was sweeping up unburnt powder off the table with wisk and a dust pan.So depending on the powder /gun it may not all be consumed in the barrel.

[Pathfinder76]

Originally Posted by Pioneer2

About Elmer Keith when he was test firing .50 BMG's at the Ogdon plant.He said he was sweeping up unburnt powder off the table with wisk and a dust pan.So depending on the powder /gun it may not all be consumed in the barrel.

Elmer Keith had about one powder to choose from.

[Dean2]

Okay, simple proof of what I said. Work up a max load in 4350 with 150 grain bullet out of an 18" barrel. Measure velocity. Work up max load with Benchmark and all other components exactly the same. Measure velocity. Also assess both max loads for accuracy. Come back and tell me which was faster and more accurate.

Last one I proved it with was a 20" barrel 308. With a 130 grain bullet and 4895 I can get 3150 fps, 1/2" groups and no pressure signs. With Varget and CFE the best I could get was 2900 fps before pressure signs showed up, accuracy at 2900 was about 1 inch. According to Hodgdon's load data, out of a 24" barrel max velocity with Varget should be virtually the same as it is with 4895, but 4895 is significantly faster burning. It also tolerates reduced loads well for playing around with cast bullets.

I have done the same validation with short barreled 375s that burn north of 80 grains of powder, as well as short barreled 300 Win Mags. Once you actually try it you will be surprised what using the correct burn rate powder, within the published range of powders and loads for that cartridge, will do for the performance of your short barreled guns.

[Pioneer2]

Originally Posted by chuck

Elmer Keith had about one powder to choose from.

Point being all powder is not necessarily burned in the barrel. His reputation and life experiences would make him an expert IMO.

[sako1]

Originally Posted by chuck

Why would accuracy have been affected?

A longer barrel means you are closer to the target 😁

[amosfella]

Originally Posted by Dean2

All the powder is burned in far less than 18.5". The issue with the shorter barrel is you have less length where the expanding gases are enclosed and acting on the bullet, that is why a faster powder is recommended in shorter barrels. It builds pressure faster and hits peak pressure sooner allowing for more velocity out of the shorter barrel. It has nothing to do with being able to burn all the powder, that happens with the fastest or slowest. I would stay with recommended powders but use the fastest powder that still produces top velocities with the desired bullet weight. Hope this helps.

For example, with a 150 grain bullet I would pick Benchmark over 4350.

Not necessarily correct. My friend and I had 45-70 guns. He had the 24" barrel and I had a 18.5" guide gun. We loaded some rounds with IMR 7828 (IIRC?) and all the powder would burn in his gun, but I still had unburned powder in the cases in my gun.

We were trying to get black powder equivalent in the guns.

[YYC338]

Originally Posted by amosfella

Not necessarily correct. My friend and I had 45-70 guns. He had the 24" barrel and I had a 18.5" guide gun. We loaded some rounds with IMR 7828 (IIRC?) and all the powder would burn in his gun, but I still had unburned powder in the cases in my gun.

We were trying to get black powder equivalent in the guns.

I'm not entirely sure barrel length was the issue here. IMR 7828 is an extremely odd powder for a straight (almost) wall case like the 45-70.

Why did you use that one?

[Dean2]

Originally Posted by amosfella

Not necessarily correct. My friend and I had 45-70 guns. He had the 24" barrel and I had a 18.5" guide gun. We loaded some rounds with IMR 7828 (IIRC?) and all the powder would burn in his gun, but I still had unburned powder in the cases in my gun.

We were trying to get black powder equivalent in the guns.

So first off, where did u find published data for 7828 in a 45-70. Second, 7828 is a REALLY slow burning powder, far slower than anything usually used in that cartridge. If you were trying for BP equivalent loads u should have been using 4759, Trail Boss, reduced 4895 loads or real black powder. There are also low pressure trap door loads published. Finally unburned powder in the case indicates an ignition problem. When most people talk about unburned powder they are talking about unburned grains in front of the muzzle. My bet is you aren't crimping, and using regular rifle primers and not getting complete ignition. 7828 is notoriously difficult to light off. Even in the 7 Rum I have to use FED 215 primers as CCI mag primers won't light off the 95 grain charges reliably. What the longer barrel length is doing is masking the poor ignition of this far too slow powder.

[Salavee]

Originally Posted by Dean2

Some of you guys need to seriously do some reading on powders, burn rates, pressure and the pressure curves different powders produce. If it was just a matter of running the slowest powder no one would bother producing data for so many load combinations for the same cartridge.

Here is about the least technical, simplest layman explanation I could find quickly. If you do some research there is a tremendous amount of very good, detailed information to be had but some of it does get very technical. Hope this helps.

https://www.outdoorhub.com/how-to/20...wder-charging/

So much Hoakey on this forum regarding powders and thier uses it's disgusting.

[marxman]

Originally Posted by Dean2

Okay, simple proof of what I said. Work up a max load in 4350 with 150 grain bullet out of an 18" barrel. Measure velocity. Work up max load with Benchmark and all other components exactly the same. Measure velocity. Also assess both max loads for accuracy. Come back and tell me which was faster and more accurate.

Last one I proved it with was a 20" barrel 308. With a 130 grain bullet and 4895 I can get 3150 fps, 1/2" groups and no pressure signs. With Varget and CFE the best I could get was 2900 fps before pressure signs showed up, accuracy at 2900 was about 1 inch. According to Hodgdon's load data, out of a 24" barrel max velocity with Varget should be virtually the same as it is with 4895, but 4895 is significantly faster burning. It also tolerates reduced loads well for playing around with cast bullets.

I have done the same validation with short barreled 375s that burn north of 80 grains of powder, as well as short barreled 300 Win Mags. Once you actually try it you will be surprised what using the correct burn rate powder, within the published range of powders and loads for that cartridge, will do for the performance of your short barreled guns.

Well I can’t argue that I have not done short and long barreled comparisons. I did look at hodgdons site though and 4350 is 120 FPS faster than benchmark in a 24 inch barrel. If it loses 30 FPS per inch that’s a loss of 180 FPS at 18 inch barrel length. The benchmark can only lose 10 FPS per inch or a total of 60fps to arrive at the same velocity as the 4350 both in 18 inch barrel.i say it’s not possible that the 4350 loses velocity that much faster and that in the hodgdon gun the 4350 is still faster. No doubt the benchmark is more efficient though it uses 80 percent of the powder to get 95 percent of the velocity

[Dean2]

Originally Posted by marxman

Well I can’t argue that I have not done short and long barreled comparisons. I did look at hodgdons site though and 4350 is 120 FPS faster than benchmark in a 24 inch barrel. If it loses 30 FPS per inch that’s a loss of 180 FPS at 18 inch barrel length. The benchmark can only lose 10 FPS per inch or a total of 60fps to arrive at the same velocity as the 4350 both in 18 inch barrel.i say it’s not possible that the 4350 loses velocity that much faster and that in the hodgdon gun the 4350 is still faster. No doubt the benchmark is more efficient though it uses 80 percent of the powder to get 95 percent of the velocity

Go try it and then get back to me. The rest is extrapolation and speculation and I can guarantee based on real life knowledge that u are incorrect in your conclusions.

[KegRiver]

I have an extensive library of reloading manuals, some old, some new.

Some list load data generated from a 26 inch barrel and some with 24 or even 22 inch barrels.

One thing that stands out when I look at load data for the various length barrels in 30-06 is the differences are minor at best.

For example my Hornady #3 shows a 4064 load at 46.6 grains with a 165 grain bullet producing 2600 fps muzzle velocity out of a 22 inch barrel

My sierra #3 shows a 4064 load at 46.2 grains with a 165 grain bullet producing 2600 fps out of a 26 inch barrel.

Of course primer and case play a role as well, still it seems to me that barrel length probably has the least effect of all the variables.

I suspect that is why reloading manuals do not list loads for different length barrels.

Another thing I find significant. The charge weight difference seems to have the greatest effect which leads me to believe that messing with unpublished charges is not a good idea.

After all the original questions was;

Would you use faster powders than recommended to compensate for this?

My answer is an emphatic NO! I would not!

[6.5 shooter]

I suppose one could load a case up with nitro..(fast)
Or load the same case with black powder (slow)

The bullet may leave the muzzle at a higher or lower speed.... There is a reason reloading manuals take years and hundreds of thousands of dollars to create.....They want you to be safe!