Berger bullets optimal speed

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Kianga1971
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Berger bullets optimal speed

#1 Postby Kianga1971 » Mon Dec 21, 2020 5:35 pm

Hi all,

I have over heard shooter talking about the optimal speed to run certain projectiles.

Is there an optimal speed to run the Berger 6mm 105 VLD’s and the 7mm 180 VLD’s?

Thanks Peter

willow
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Re: Berger bullets optimal speed

#2 Postby willow » Mon Dec 21, 2020 6:11 pm

This one may generate some debate. There's two schools of thought on this one, one is certain bullets like to operate in nodes and the other is it simply doesn't matter and let the barrel tell you.

I ran Berger 105gr VLDs predominantly in a 6BRAI at 2970fps. A lot of the US guys running this cartridge support the theory that the 6BRAI likes to run between 2940-2990fps. I didn't seek that speed specifically, it's just where the bullet ended up running it's best, based on my load development.

Similar deal with the 7mm bullets, depends on your calibre though. No point running a 7SAUM at 2800fps when it can push the 180s comfortably at 2940fps.

KHGS
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Re: Berger bullets optimal speed

#3 Postby KHGS » Mon Dec 21, 2020 7:06 pm

Kianga1971 wrote:Hi all,

I have over heard shooter talking about the optimal speed to run certain projectiles.

Is there an optimal speed to run the Berger 6mm 105 VLD’s and the 7mm 180 VLD’s?

Thanks Peter


I suggest that it is not optimal bullet speed that that is being referred to, but cartridge/bullet weight optimal speed. Because cartridge/bullet weight speed is determined by chamber pressure attained with the powder charge weight burnt. So in effect it is chamber pressure that determines tune nodes, the amount of powder burnt to develop the "pressure node" and barrel length determines the bullet speed. Velocity is often used as a measure to determine a node simply because shooters do not have the means to accurately measure chamber pressure and as velocity relates to chamber pressure it is used as a gauge. Many do not understand this and over time velocity has become the "holy grail" and the fact that it is only an indicator has been lost along the way. My observations, so make of it what you will.
Keith H.

Redhawk
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Re: Berger bullets optimal speed

#4 Postby Redhawk » Mon Dec 21, 2020 8:06 pm

Fully support that Keith! All about the optimum repeatable pressure curve, and running a chronograph is easier for most than using strain gauges.

Regards
Frans

Gyro
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Re: Berger bullets optimal speed

#5 Postby Gyro » Tue Dec 22, 2020 4:17 am

For the benefit of the less experienced shooters I suggest it is important to believe that accuracy nodes ( velocity bands ) do in fact exist. Call it a pressure band if u like. How or why they exist generates very complicated theory and speculation.

So find one of those optimum velocity/pressure bands for your rifle/load combo and happy days, or so the very simplistic theory goes. But if u can widen that node by using particular tricks then you will gain a LOT !

wsftr
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Re: Berger bullets optimal speed

#6 Postby wsftr » Tue Dec 22, 2020 3:33 pm

velocity bands, pressure bands, doing what the barrel likes...all outcomes of a robust, reliable process to get to an accurate load.
Figure out what methodology you will use to get there and you are half way there...when you land at an accurate load you will most likely find it aligns with a velocity, pressure or what the barrel is telling you.
I don't believe there are shortcuts to getting to an accurate load but hindsight tells you what matters.

RDavies
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Re: Berger bullets optimal speed

#7 Postby RDavies » Fri Dec 25, 2020 8:20 am

To go back to the original question, I have read references in the internet stating that such and such bullet likes to be shot at such and such speed to work well. This is a load of rubbish, the bullet doesn't have any preference about speed as long as it is stable and is not going too fast where it starts to copper foul, or spinning to fast (from high velocity and twist rate) which will make it come apart in flight. As others mentioned, it is barrel harmonics and pressure curves which dictate nodes.
Here is an example of how bullets will work well at many speeds.
With 183 Sierras, I have used them in loads from 1500 fps up to 3070 fps with numerous accuracy nodes.
When fire forming 284 Shehane with my 8" twist barrel with no tuner, I found the following nodes with 183 Sierras
1490 fps with Trailboss
2580 fps with 2208 fire form load
2700fps with 2209 fire form load
2820 fps with full power 2209 load
2830 fps with full power 2213sc load

In SAUM with a tuner, I have a nice soft fire form load at 2830 fps but same tuner setting will work well with full power load at 2950 fps.
In a bigger case I tried a few years ago, I had a nice fire form node at 2940 fps and full power load at 3070 fps (at this speed was a definite node, but excessive copper fouling and bullets coming apart showed its limits) .

So all up, I was able to find accuracy nodes with same bullet at 1490 to 3070 fps. With a tuner I could move the node around a little, but each load had its preferred speed range, all with the same bullet.

KHGS
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Re: Berger bullets optimal speed

#8 Postby KHGS » Fri Dec 25, 2020 8:54 am

RDavies wrote:To go back to the original question, I have read references in the internet stating that such and such bullet likes to be shot at such and such speed to work well. This is a load of rubbish, the bullet doesn't have any preference about speed as long as it is stable and is not going too fast where it starts to copper foul, or spinning to fast (from high velocity and twist rate) which will make it come apart in flight. As others mentioned, it is barrel harmonics and pressure curves which dictate nodes.
Here is an example of how bullets will work well at many speeds.
With 183 Sierras, I have used them in loads from 1500 fps up to 3070 fps with numerous accuracy nodes.
When fire forming 284 Shehane with my 8" twist barrel with no tuner, I found the following nodes with 183 Sierras
1490 fps with Trailboss
2580 fps with 2208 fire form load
2700fps with 2209 fire form load
2820 fps with full power 2209 load
2830 fps with full power 2213sc load

In SAUM with a tuner, I have a nice soft fire form load at 2830 fps but same tuner setting will work well with full power load at 2950 fps.
In a bigger case I tried a few years ago, I had a nice fire form node at 2940 fps and full power load at 3070 fps (at this speed was a definite node, but excessive copper fouling and bullets coming apart showed its limits) .

So all up, I was able to find accuracy nodes with same bullet at 1490 to 3070 fps. With a tuner I could move the node around a little, but each load had its preferred speed range, all with the same bullet.


Correct Rod, pretty much what I said, but in a little more detail, well explained!!
Keith H. =D> =D>

bruce moulds
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Re: Berger bullets optimal speed

#9 Postby bruce moulds » Fri Dec 25, 2020 9:35 am

rod,
i think the spinning too fast thing deserves more discussion.
in my experience with barrels we get and available bullets, it is impossible to overspin a bullet.
and example is 50 gn bullets in an 8" twist 22 cal.
the old s.g . being optimum at 1.5 has proven to me to be a furphy, and that higher s.g. is superior for long range shooting.
in short range shooting, a lower s.g. is better due to reduced precession and nutation, but we do not have the luxury of short bullets and the slow twists that suits them.
when you get into the longer ranges, the bullet has to go through a lot more condition, and a bit more stability becomes your friend, in order to minimize wayward shot issues.
bruce.
"SUCH IS LIFE" Edward Kelly 11 nov 1880
http://youtu.be/YRaRCCZjdTM

bruce moulds
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Re: Berger bullets optimal speed

#10 Postby bruce moulds » Fri Dec 25, 2020 10:14 am

a little more on my previous post.
when our bullets go through differing condition, wind strength/direction, the forces on them change, which induces another precession and nutation.
the fact that we get spindrift proves that our long bullets to some degree steer themselves due to the yaw of repose.
while precessing and nutating, they are also steering themselves a little, enlarging the group..
a faster twist minimalizes this.
bruce.
"SUCH IS LIFE" Edward Kelly 11 nov 1880

http://youtu.be/YRaRCCZjdTM

Wingnut
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Re: Berger bullets optimal speed

#11 Postby Wingnut » Fri Dec 25, 2020 10:36 pm

Rod, you do realise you’ve contradicted yourself with the last line that stated “each bullet has it’s preferred speed range”, that kinda agrees with the very broad statements that people make where they say a particular projectile likes to be run around a particular speed. I’d say they’re really saying a node corresponds with the projectile running around that particular speed. The 10fps between the 2209 and 2213sc velocities is negligible in the scheme of things and tends to support the assumption.

RDavies
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Location: Singleton NSW

Re: Berger bullets optimal speed

#12 Postby RDavies » Sat Dec 26, 2020 1:17 am

Wingnut wrote:Rod, you do realise you’ve contradicted yourself with the last line that stated “each bullet has it’s preferred speed range”, that kinda agrees with the very broad statements that people make where they say a particular projectile likes to be run around a particular speed. I’d say they’re really saying a node corresponds with the projectile running around that particular speed. The 10fps between the 2209 and 2213sc velocities is negligible in the scheme of things and tends to support the assumption.

No, I said quote"but each load had its preferred speed range, all with the same bullet" EACH LOAD
Each load, all with the same bullet.
Each load gave different barrel harmonics which preferred a different speed, anywhere between 1490 fps to 3070 fps.
Generally harmonic nodes are around 120-130 fps apart with each combination.

Wingnut
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Re: Berger bullets optimal speed

#13 Postby Wingnut » Sat Dec 26, 2020 3:15 am

Erm, what? Not sure if I’m missing your point but I’m finding it really hard to see what relevance that has to the OP’s question. Which I tend to believe is suggesting most people tend to settle on the node that sits just below Pmax for their rifle / cartridge set up. How does this effect the fact that multiple people, using different barrels of similar length and profile tend to find accuracy nodes around the same velocities. Are there nodes at lower velocities, yes, are there nodes at higher velocities, yes. Do people tend to talk about the velocity that performs well and won’t ruin your brass as a preferred speed, yup.

But I do find it rather interesting that two different powders in your cartridge / projectile combination both found an accuracy node around the same velocity. Again, that tends to support the theory that a particular style projectile will perform similarly across various rifles so long as they’re are similarities between barrel profiles for each load combination. I’d be interested to see if loading up some lower loads with 2213 would yield a similar result to that with the 2209.

RDavies
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Re: Berger bullets optimal speed

#14 Postby RDavies » Sat Dec 26, 2020 7:36 am

Wingnut wrote:Erm, what? Not sure if I’m missing your point but I’m finding it really hard to see what relevance that has to the OP’s question. Which I tend to believe is suggesting most people tend to settle on the node that sits just below Pmax for their rifle / cartridge set up. How does this effect the fact that multiple people, using different barrels of similar length and profile tend to find accuracy nodes around the same velocities. Are there nodes at lower velocities, yes, are there nodes at higher velocities, yes. Do people tend to talk about the velocity that performs well and won’t ruin your brass as a preferred speed, yup.

But I do find it rather interesting that two different powders in your cartridge / projectile combination both found an accuracy node around the same velocity. Again, that tends to support the theory that a particular style projectile will perform similarly across various rifles so long as they’re are similarities between barrel profiles for each load combination. I’d be interested to see if loading up some lower loads with 2213 would yield a similar result to that with the 2209.


The relevance to the OPs question is that the bullet does not have any preferred speed. Most people would end up settling on similar speeds with similar cartridges and barrel lengths as that is where the barrels harmonic node ends up being with that cartridge and barrel length. If you use a tuner you can move this node around so the bullet shoots well at different velocities. As for loading up lower loads with 2213sc, whether it will behave in a similar way to 2209, yes, you could load it to a lower node, which I often do for fire forming, and without a tuner the nodes are once again 120-130 fps apart. Without using a tuner, it is not surprising the 2213sc node is very slightly higher than with 2209 as to keep the same barrel exit time, with a slower burning powder, with its flatter pressure curve, its muzzle velocity will be a little higher than with the faster peaking 2209.

Gyro
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Re: Berger bullets optimal speed

#15 Postby Gyro » Sat Dec 26, 2020 8:02 am

Yeah damn right what would that guy know haha ….

But seriously, when someone asks a question here I nearly always look to see when they joined just because it may give me a clue how much they already know. Rod has given me some valuable info stating that potentially nodes can exist over a huge velocity/pressure range. I sure haven’t done that amount of work to know that’s true ! I’m basically a lazy bastard who kind-of knows when the gun is going well then I leave it alone and focus on the myriad other details that can get you shooting well. That’s CONSISTENTLY well, because anyone can shoot well now and again.

I learnt the hard way that nodes do exist. For a time I didn’t just believe it as after all u can believe in many things in this game that are not properly proven …..

Accuracy nodes do exist. You know u have found one when the rifle starts to group its best, when the loads either side of the “best load” show decreasing accuracy. If only it was so simple. The best load today, or last week, may not shoot well next week. Why ? Maybe u developed your “best” load on a particularly hot day, but the following week the ambient temperature is considerably lower and now the gun won’t group tight. This particular scenario is VERY common, but u can mitigate against this happening by firstly using a powder that has a relatively good tolerance to being used across different temp ranges.

This is one example among many re what happens and quite frankly I would suggest that many shooters just don’t have gear good enough, or enough technique or setup understanding ( or just general shooting knowledge gained over a long period ) to really properly know what’s actually going on re when they are in a node or not. I’m ten years into F Class shooting and am still learning. No I don’t have a tuner but I do have a 750gm weight on the front of my F Gun because I believe it helps. It certainly helps the current gun anyway.

Apologies for teaching the experienced shooters how to suck eggs !


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