Optimum barrel time: great theory or bunk?

[Bbracken667]

I am currently experimenting with OBT (Optimum Barrel Time). There are a few apps I am using in this pursuit. GRT (an online free use program similar to QuickLoad). A phone app called Barrel time, which supplies barrel nodes based on barrel length. Plus incorporating where logical Hornady, Hodgdon, Sierra and VihtaVouri load apps.
The theory, as I understand it, relates to barrel harmonics and timing the bullet using powder charges, seating depths and expected calculated results.
I think, logically, we should be able to calculate charge and seating depths to get close to the harmonic node that best suits the powder/bullet combo and run load development in a material and time efficient manner.
I heard about OBT some time back but never pursued it. Being retired has afforded me the time to investigate and experiment. Links below, and more to come

Optimal Barrel Time Paper

 

[Bbracken667]

Just an fyi: with GRT make sure your inputs are as accurate as possible. GIGO (garbage in, garbage out)
I have yet to look into the GRT node tool. So much to learn.

 

[R_A_W]

Believe The Target podcast has a number of discussions with very knowledgeable people.

Chris Long, Mark Gordon, John Krieger & I think a few others (Jack Neary?) discuss OBT . I’d recommend the Chris Long episode, as he established the theory

I got a great laugh out of Cortina visibly realizing Krieger has zero clue who Cortina is when Krieger briefly discussed barrel tuners

 

[Bbracken667]

Believe The Target podcast has a number of discussions with very knowledgeable people.

Chris Long, Mark Gordon, John Krieger & I think a few others (Jack Neary?) discuss OBT . I’d recommend the Chris Long episode, as he established the theory

I got a great laugh out of Cortina visibly realizing Krieger has zero clue who Cortina is when Krieger briefly discussed barrel tuners

Thanks! I will give it/them a look. I have a ton of material to review re: GRT, and have Long’s paper, which seems quite logical. I want to become proficient enough to be able to predict best loads, or at least narrow the field down before entering load development in earnest.

 

[R_A_W]

The Chris Long episode is most pertinent - it’s been 20 years since he wrote the paper, so some of his theory has evolved & he discusses that a bit

Mark Gordon doesn’t really talk about OBT specifically, he discusses seating depth

The Krieger episode is full of all kinds of info, it’s worth a listen anyways

Edit: The Frank Green episodes are excellent as well

 

[Dstoenner]

I don’t have quickload but i do have and use GRT. The great thing about GRT is that if you put at least 1 velocity of a given load it will use all of your input as a system and calculate new values for your powder. Then what it says for a given node of OBT is pretty close. I still have to go close to that node and test .2 gn above and below. The best is to use 5 varying powder levels with velocity input.

It is this treating of your whole gun and load as a system that makes GRT so great. Also don’t forget to copy and paste the 2 powder variables from the obt run back into your original file.

And to answer the question asked, yes it is real. It is the nature of a bullet being fired and it creates an impulse function which travels quickly in steel. You just can’t get away from the laws of physics

David

 

[Bbracken667]

I don’t have quickload but i do have and use GRT. The great thing about GRT is that if you put at least 1 velocity of a given load it will use all of your input as a system and calculate new values for your powder. Then what it says for a given node of OBT is pretty close. I still have to go close to that node and test .2 gn above and below. The best is to use 5 varying powder levels with velocity input.

It is this treating of your whole gun and load as a system that makes GRT so great. Also don’t forget to copy and paste the 2 powder variables from the obt run back into your original file.

And to answer the question asked, yes it is real. It is the nature of a bullet being fired and it creates an impulse function which travels quickly in steel. You just can’t get away from the laws of physics

David

Lovely! As I play with this, learning the software as I go, I am convinced this is a valuable tool that I will use a lot. Have not tested the OBT function yet, but I expect in a couple weeks or so I will be on that
Thanks for the input!!

 

[Bbracken667]

Believe The Target podcast has a number of discussions with very knowledgeable people.

Chris Long, Mark Gordon, John Krieger & I think a few others (Jack Neary?) discuss OBT . I’d recommend the Chris Long episode, as he established the theory

I got a great laugh out of Cortina visibly realizing Krieger has zero clue who Cortina is when Krieger briefly discussed barrel tuners

Watched this today. Excellent! Thanks!

 

[kthomas]

I've yet to be convinced that there's a magical frequency that your barrel should resonate at for optimum precision.

 

[Dstoenner]

Lovely! As I play with this, learning the software as I go, I am convinced this is a valuable tool that I will use a lot. Have not tested the OBT function yet, but I expect in a couple weeks or so I will be on that
Thanks for the input!!

Indirectly. My 1000 fclass gun is 6x47L. Before i knew about grt i did a full load development cycle. 10 loadings .2 gn apart. I recorded velocity for the 4 rounds i shot at each loading. From that i picked 39.3 with a velocity of 2975 and an sd of 5. Fast forward 2 years and i get into grt. So i asked the same question. So i plugged in all 10 load statistics and ran an obt. It came out 39.4 at about the same velocity as i had come up with. I picked 39.3 because it was between 2 good points in my testing. That is what convinced me it is good


David

 

[Doom]

I've yet to be convinced that there's a magical frequency that your barrel should resonate at for optimum precision.

A given barrel vibrates at its natural frequency. It does not depend on charge weight. Barrel time affects where the barrel is pointed at a given time. Chris Long's theory isn't directly related to barrel position but where the acoustic wave is in the barrel. I don't know that anyone has proven that the theory is correct but it seems to in many cases.

 

[R_A_W]

Elaborating on Doom's comment... you're not aiming to change the frequency or harmonics w/ OBT. You're just optimizing bullet timing for a given barrel's frequency parameters. IMO barrel tuners are more woo woo than OBT, yet those seem to be highly effective for many. Relevant quotes from the paper:

The theory states that if the bullet leaves at the time when the rate of change of the muzzle diameter is minimum, the dispersion will be at a minimum, and any small variations in exit time caused by load variations will have a minimum effect on the dispersion.

One of the major observations was that OCW loads tend to work well in almost any rifle, regardless of barrel length. This observation forced us to abandon the concept of a simple harmonic vibration as being the cause of dispersion.

Since the pulse is changing the bore diameter as it passes back and forth, it seems reasonable that the bullet frictional load is also changing as the bore diameter changes. During the first two or three trips back to the chamber end, the bullet has moved by less than two inches, and the pressure is at or near maximum, Figure 7. If the bore constricts, it will cause the bullet to be retarded some, and thereby increase the pressure rate of increase. Conversely, as the bore expands after the first part of the pulse passes, the bullet will be looser, and the pressure increase rate will drop. In other words, the pulse, by interacting with the bullet during the critical first few inches, can dramatically change the burn characteristics by modulating the bullet retardation forces.

I'm curious how the frictional load affects monolithics & moly coated bullets v. conventional uncoated jacketed bullets.

I don't currently use QL or GRT. The closes I get to OBT is w/ seating depth test during load development, like most. Regardless, Long's paper is interesting and worth a read. It's actually fairly short & clearly written.

 

[Bbracken667]

I've yet to be convinced that there's a magical frequency that your barrel should resonate at for optimum precision.

That is the purpose behind my testing. I am not in any hurry, but confidence is high. There is a lot of evidence to support such a theory. Adjusting charge would obviously change timing, and so would seating depth, to a lesser degree. I have played with a crude form of harmonic timing by sliding a weight around to different spots on the barrel. This also produces changes in poi. I am at a loss to explain that effect without the existence of some sort of harmonic timing.

 

[SharpShooterSER]

In past few years I've done more than 20 different calibers and loads using OBT as a starting point and it got me to the desired result much faster than I used to achieve it before using it.

 

[Doom]

That is the purpose behind my testing. I am not in any hurry, but confidence is high. There is a lot of evidence to support such a theory. Adjusting charge would obviously change timing, and so would seating depth, to a lesser degree. I have played with a crude form of harmonic timing by sliding a weight around to different spots on the barrel. This also produces changes in poi. I am at a loss to explain that effect without the existence of some sort of harmonic timing.

Just to assure you a barrel behaves like a beam struck by a hammer or one of the tines on a tuning fork. As such its motion is sinusoidal and when viewed versus time there are places where the displacement is more rapid than at others.

 

[John Glidewell]

OBT calculator here. http://www.the-long-family.com/optimal barrel time.htm

I find a safe max (true QL) and look back around 1.5 to 2 grains for either a 1 or .5 barrel time. They always shoot in that area. Has made load development real easy. Just make sure the inputs are correct, and measure your barrel. Bolt face to crown. It makes a difference. Just because you ordered a 26" barrel does not mean it is a true 26".

 

[Bbracken667]

OBT calculator here. http://www.the-long-family.com/optimal barrel time.htm

I find a safe max (true QL) and look back around 1.5 to 2 grains for either a 1 or .5 barrel time. They always shoot in that area. Has made load development real easy. Just make sure the inputs are correct, and measure you barrel. Bolt face to crown. It makes a difference. Just because you ordered a 26" barrel does not mean it is a true 26".

Exactly. Mine is 24.3”. I was shocked when I first discovered that, then realized that it was probably cut to mm but described as 24” in the US.
Also: bullet length seems spectacularly off. By more than just manufacturing tolerances, easily.
Also: available cartridge volume. There is a difference between new and fire formed cases and the value that exists in the program. Measure your own specifics in every possible instance.
I have redone my calculations numerous times simply because assumptions turn out wrong on almost every case. The 24 vs 24.3 created a significant difference all by itself. Thank the Lord I have been waiting until confidence is high to actually start the handloading or I would have expended quite a bit of materiál by this point. I am surpassing the carpenter’s credo: measure twice, cut once.

 

[Bbracken667]

Just to assure you a barrel behaves like a beam struck by a hammer or one of the tines on a tuning fork. As such its motion is sinusoidal and when viewed versus time there are places where the displacement is more rapid than at others.

Oh absolutely! There has never been any doubt about that. My background is scientific and mathematic. My question, as posed, is regarding the application of the theory.
For instance, you mentioned 2 effects that arise from the firing of a cartridge. Do their “frequencies” coincide or do they cancel at some point? There is the pressure wave that initially travels back, before rebounding forward, then there is the wave that would be associated with contraction/expansion of the barrel, along with the associated contraction/expansion of the bore diameter.
Very complex interactions and capturing that into a simulation would be incredibly complex. Or, perhaps, the simplest approach is the best. Occam’s Razor.

 

[spife7980]

Barrel Harmonics Mode Shape Movies

 

[brianf]

When do we start arguing about tuners ?

 

[Bbracken667]

Barrel Harmonics Mode Shape Movies

Thanks!! And I hate you! LOL I fear I may never get through all the information I have now. Seriously though, thank you for this link.
And so, the plot thickens!
The Game is afoot!

 

[R_A_W]

The Tim Sellars episode on positive compensation was also great. Seems more impactful for loads with high SD/ES... not sure if this kind of load testing is something I want to incorporate.

 

[Macht]

The short answer to the original question: it's complete bunk.

A longer answer to the original question: anyone who has measured or semi-accurately modeled barrel dynamics will cringe at the word "harmonics". If you end up reading through the VarmintAl page posted above you'll notice that he documents his process of discovery. He started off believing that harmonic (sinusoidal) behavior best described barrel motion, but his modeling and experiments led him to realize that what the bullet causes/encounters is just a transient forced response (precursor to harmonic motion). Barrels absolutely vibrate in a harmonic manner.... after the bullet is gone.

You'll find similar thoughts expressed by Jeff Siewert, formerly of ArrowTech, a company that sells a piece of software (BALANS module for PRODAS) capable of modeling both barrel motion and projectile balloting behavior. You can also discover through their software that frictional resistance curves (the whole basis of OBT theory) don't change the results much at all.

Finally, the fundamental calculations that underly OBT are flawed. The speed of sound calculations ignore losses due to shear waves, which cause the actual speed at which a stress wave travels from one end of a barrel to the other to be slightly slower than the speed of sound used in the calculations. Additionally, the expansion/contraction caused by such a stress wave has an amplitude smaller than the manufacturing tolerances for most commercial barrels (tenths, .000X), so any contraction present is in the noise.

 

[R_A_W]

What does that leave to explain bullets that perform materially better at multiple discrete seating depths, but poorly in between?

thoughts expressed by Jeff Siewert

Any links to this available?

 

[Jumper]

The short answer to the original question: it's complete bunk.

A longer answer to the original question: anyone who has measured or semi-accurately modeled barrel dynamics will cringe at the word "harmonics". If you end up reading through the VarmintAl page posted above you'll notice that he documents his process of discovery. He started off believing that harmonic (sinusoidal) behavior best described barrel motion, but his modeling and experiments led him to realize that what the bullet causes/encounters is just a transient forced response (precursor to harmonic motion). Barrels absolutely vibrate in a harmonic manner.... after the bullet is gone.

You'll find similar thoughts expressed by Jeff Siewert, formerly of ArrowTech, a company that sells a piece of software (BALANS module for PRODAS) capable of modeling both barrel motion and projectile balloting behavior. You can also discover through their software that frictional resistance curves (the whole basis of OBT theory) don't change the results much at all.

Finally, the fundamental calculations that underly OBT are flawed. The speed of sound calculations ignore losses due to shear waves, which cause the actual speed at which a stress wave travels from one end of a barrel to the other to be slightly slower than the speed of sound used in the calculations. Additionally, the expansion/contraction caused by such a stress wave has an amplitude smaller than the manufacturing tolerances for most commercial barrels (tenths, .000X), so any contraction present is in the noise.

I watched the video with Eric Cortina and Chris Long discussing OBT. I'm not sure why you say its bunk? Its a phenomenon thats while it may not be easily observable, is clearly repeatable. One can form a hypothesis around it and test it's veracity. Eric Cortina did absolutely no load testing with a new caliber (284 shehane) but tailored his load around the nodes that OBT predicted should be present and went to a match and won it and set a course record with it.

Frictional resistance curves didnt have much to do with the OBT theory. It probably has some effect but its primary benefit is timing the bullets exit from the muzzle when its not distorted by the impulse.

 

[Cascade Hemi]

Eric Cortina anecdotes don't prove or disprove anything.

 

[Doom]

I believe he is referring to Jeff's book Ammunition, Demystified. He has a section on Gun Dynamics and discusses barrel time in a fair amount of detail, especially as it relates to dispersion. I was impressed with the book and I have it as an Apple Book. If you choose to get it I will note in mine some of the figures do not display correctly.

Unfortunately I can't copy and paste the material due to copyright.

 

[Secant]

I currently agree that OBT is bunk. Below is a link to a thread that went through OBT (starting on page 4, I think).

PRS Talk - How does being in a “node” actually matter?

So 41.2 grains of H4340 in a Peterson case with a 140 hybrid should shoot pretty damn well in just about any match 6.5 chamber? I’m running 41.0 grains of H4350 for Berger 140 Hybrids in a Hornady case with large rifle primers, and easily 0.3-0.4MOA at 2753 fps. Just load to the factory ammo...

www.snipershide.com

 

[John Glidewell]

That thread is from 3 years ago. Still using OBT. Still working for us. I have done profiles for others here too and it worked. To each their own.

 

[R_A_W]

Below is a link to a thread that went through OBT (starting on page 4, I think).

Looks like an interesting thread, but I only read pages 3-6 fairly quickly. It looked like the OBT-related comments were really directed at the OBT theory as presented 2 decades ago in the 2004 paper (I may have missed something & will have to reread tonight).

Long has evolved his theory (but has not updated his paper)... as I understand it, he still focuses on the Poisson effect, but has moved away from frictional load & now focuses on combustion gasses at the time the bullet exits the barrel (10:21-15:30 from the Podcast). Specifically, bore diameter changes/inconsistencies near the muzzle around the time of the bullet's exit allows the combustion gasses to destabilize the projectile.

If Long's theory is correct (& my understanding thereof), the goal is to find a load that appropriately times the bore diameter for consistency, thereby allowing for the bullet to exit when any impulses that induce/cause bore diameter variances have traveled back towards the chamber. Correct me if I've misunderstood something...

@Macht did you complete/publish your paper(s)?

 

[Jumper]

Eric Cortina anecdotes don't prove or disprove anything.

Agreed. But we're dealing here in the realm of theories. And until this phenomenon can be proven or disproven, anecdotes will carry a lot of weight.

It also seems like the OBT concept has been thoroughly validated: i.e. There is an optimum time for the bullet to exit the barrel. Bullet group dispersion on targets that change with velocity demonstrate this clearly. Why this happens is the question.

 

[918v]

Agreed. But we're dealing here in the realm of theories. And until this phenomenon can be proven or disproven, anecdotes will carry a lot of weight.

It also seems like the OBT concept has been thoroughly validated: i.e. There is an optimum time for the bullet to exit the barrel. Bullet group dispersion on targets that change with velocity demonstrate this clearly. Why this happens is the question.

Also, group dispersion that changes with coal.

 

[Bmghunter]

Wondering if the theory can calculate the optimal muzzle velocity by barrel length. The timing aspect is how long the bullet stays in the barrel, which is a time of acceleration. In theory, if given a muzzle velocity and distance (barrel length), you could calculate the time to accelerate (barrel time). Or in other words, knowing the theoretical optimal barrel times for a barrel length, you should be able to calculate an optimal muzzle velocity that matches the obt for the barrel length.
Regardless of whether obt is bunk or not, I'm wondering whether the (Not optimal) barrel times vary for a given length will vary for the same muzzle velocity.
If barrel time don't vary for a given muzzle velocity and barrel length, you should be able to see if your best loads with a given muzzle velocity can be calculated back to a barrel time, and then see if it lines up with obt.

 

[Baron23]

Barrel Harmonics Mode Shape Movies

I'm sure I'm missing something simple here, but I have never quite understood why all of these analysis show the barrel moving in only the vertical axis while I would think that the vectors of all forces during internal ballistics could sum into any direction around the barrels bore.

 

[spife7980]

I'm sure I'm missing something simple here, but I have never quite understood why all of these analysis show the barrel moving in only the vertical axis while I would think that the vectors of all forces during internal ballistics could sum into any direction around the barrels bore.

"These are the first 8 mode shapes and frequencies. Each bending mode (like Mode #1) is on one plane, but there was another identical mode in another plane at the same frequency that was not shown to save space."

 

[Baron23]

"These are the first 8 mode shapes and frequencies. Each bending mode (like Mode #1) is on one plane, but there was another identical mode in another plane at the same frequency that was not shown to save space."

So, bending mode in two planes...so, why does Mode #1 have to be in the vertical plane. And what "another identical mode in another plane"?

So, if I have mode #1 that has to be in the the vertical plane (??) and the other...identical in amplitude and timing (??)....in some other plane...like any other plane...any degree of direction about the 360? And depending on what direction the "other plane" is in then it sums with the vertical plane mode for an end result in any direction?

I've forgotten the little bit of physics I once knew...but a barrel muzzle is going to move in some direction (which I can't see as needing to be in the vertical...could be in any direction) and yes, this movement can be disected into vertical and horizontal vector components (or really any other components you may like) but that doesn't mean; 1) that the two vectors need in any way to be "identical" and; 2) the resulting movement (vector sum) is in the either of those planes. So, what's the value?

Still doesn't make sense to me but I'm def not as smart as I once thought I was! haha

 

[spife7980]

I dont know, just adjust your powder and seating depth until it shoots good.

 

[brianf]

Wondering if the theory can calculate the optimal muzzle velocity by barrel length. The timing aspect is how long the bullet stays in the barrel, which is a time of acceleration. In theory, if given a muzzle velocity and distance (barrel length), you could calculate the time to accelerate (barrel time). Or in other words, knowing the theoretical optimal barrel times for a barrel length, you should be able to calculate an optimal muzzle velocity that matches the obt for the barrel length.
Regardless of whether obt is bunk or not, I'm wondering whether the (Not optimal) barrel times vary for a given length will vary for the same muzzle velocity.
If barrel time don't vary for a given muzzle velocity and barrel length, you should be able to see if your best loads with a given muzzle velocity can be calculated back to a barrel time, and then see if it lines up with obt.

Anything can be calculated once the variables are given a value.

That’s why all the “voodoo” of reloading is argued about to no end. If everything works then nothing works.

At the speeds and times we are dealing with it’s all out in the wash.

What happens if one bullets jacket is slightly thicker etc (Just some stupid examples)

Is it slower

does it change the “bulge”

does the thicker jacket cause more initial pressure so the timing is off

Does it shoot “better” because it’s more engaged with rifling yet outside the “harmonics”

How much is the lead core flexing and changing shape

There are a million variables that cannot be accounted for, and if the are they cannot be measured with in reason.

If all the theory mattered then why is the answer always;

Lapua brass
Berger bullet
Weigh to the grain
Seating depth adjustment or touch lands

No matter what the cartridge that always produces the best results. Across 10s of thousands of rifles from custom to crap.

Fun to talk about but at the end of the day …but it’s not going to make a difference timing to a possible computed velocity number compared to seating depth and velocity.

They may cross paths or may not but at the end of the day ultimate accuracy/consistency will be limited by components and rifle workmanship no matter how the process was created. One maybe shorter or requiring less work but that is still a coin flip in the grand scheme.

I could be totally wrong, and I wish I was but it’s really not that hard to get the best out of firearm without using a program.

And if all the computed results are not accompanied by internal or piezio pressure recording it’s all a waste of time. Unless you can “see” inside you can always make the numbers match at the end…just like a good accountant can lol

 

[AccuSol-ERN]

I can't speak to OBT or theory, but one thing I have noticed based on actual results. The straighter the bore and more even the barrel wall (i.e. referenced to bore center) the wider the "node" and more forgiving it will be. In my layman's terms, the better the barrel characteristics mentioned above the smaller the wave amplitude which yields a smaller change given a set time interval. Take a garden hose......the straighter the hose is the less it moves (vertically/horizontally) when the water is turned on full blast.

High amplitude barrels can still shoot very well.....the ammo just needs to be more velocity consistent.

Of course, all this is given everything else is PERFECT......barrel bore consistency/quality, gunsmithing machining and installation, ammo components and assembly.

Personally, I think there are larger variables to be chased. I see plenty of recent examples of offset chambers/freebores and oversize chambers.

Unless you get a chamber that reads .0000" on a .0001" res indicator with 1/2" needle, you are leaving science on the table. I have yet to see this without a slight heartbeat or perfectly referenced to groove diameter. Even the shops that cheat with greater than .0005" bullet clearance ground into their match reamers freebore......it may look perfect on a borescope but slap it in the lathe and indicate it to .0000" and check it......Ooops......You can argue clearance is clearance......but the bullet engages the lands somewhere......that somewhere is still going to be slightly off.

Probably not even worth $.02......but figured I would contribute.

Ern

 

[CK1.0]

Put me down as a non believer.

The longer I do this shit, the more I’m convinced most legacy reloading dogma is total nonsense.

I don’t even do load development anymore really. I just pick a speed and pick a seating depth out of the air, and as long as I drop powder to the kernel and make sure every round turns out the same as the next, all it does is get me the smallest groups I’ve ever shot and half-MOA out past 1000 yards every time.

 

[brianf]

Put me down as a non believer.

The longer I do this shit, the more I’m convinced most legacy reloading dogma is total nonsense.

I don’t even do load development anymore really. I just pick a speed and pick a seating depth out of the air, and as long as I drop powder to the kernel and make sure every round turns out the same as the next, all it does is get me the smallest groups I’ve ever shot and half-MOA out past 1000 yards every time.

Witch craft!!!!!!!!!

 

[powdahound76]

This is all gayer than aids.
Jerking off over a computer vs handling a rifle and shooting.


Get an Ern or Fritz turned barrel.
Break it in.
Test loads or pick a known good load with sierra or bergers using Perterson or Lapua brass.
Shoot 5 shot groups in .2s.
1 Ern barrel gave me .169” for 5 on shots 11-15 with a known load and VLD 15 thou off.
And Im a mediocre trigger slapper on my best days.

Same goes with my Fritz turned barrels
They all shoot small.

Several others that run around .5 on average (more than good enough for me) and not .2 reliably like those.


And cause it happened, I have a Proof CF prefit that gives me 3 shots right around .250” measuring with calipers and not an electronic program.
No testing.
Just a good load in Lapua SRP 6.5 brass and 140 Bergers (loaded by Copper Creek no less)

 

[Emerson0311]

Indirectly. My 1000 fclass gun is 6x47L. Before i knew about grt i did a full load development cycle. 10 loadings .2 gn apart. I recorded velocity for the 4 rounds i shot at each loading. From that i picked 39.3 with a velocity of 2975 and an sd of 5. Fast forward 2 years and i get into grt. So i asked the same question. So i plugged in all 10 load statistics and ran an obt. It came out 39.4 at about the same velocity as i had come up with. I picked 39.3 because it was between 2 good points in my testing. That is what convinced me it is good


David

So the old way came up with the same answer as the new tech way. Does the new way save effort and time? To an electronic geek, probably. For a guy like me, it’s probably an exercise in misery, like grocery shopping in a tiny 2 seat sports car.

For the software folks with a proper physics education, is the barrel impulse wave just about barrel length, or does profile and maybe material change the optimal dwell time? How much does powder burn rate and volume of powder change results, ie. less but faster powder producing the same projectile velocity?
The algorithms driving the software are what tell us how flexible and error prone the results are. I don’t have the brainpower to dig that deep, but surely someone who does understands my question.

 

[AccuSol-ERN]

This is all gayer than aids.
Jerking off over a computer vs handling a rifle and shooting.


Get an Ern or Fritz turned barrel.
Break it in.
Test loads or pick a known good load with sierra or bergers using Perterson or Lapua brass.
Shoot 5 shot groups in .2s.
1 Ern barrel gave me .169” for 5 on shots 11-15 with a known load and VLD 15 thou off.
And Im a mediocre trigger slapper on my best days.

Same goes with my Fritz turned barrels
They all shoot small.

Several others that run around .5 on average (more than good enough for me) and not .2 reliably like those.


And cause it happened, I have a Proof CF prefit that gives me 3 shots right around .250” measuring with calipers and not an electronic program.
No testing.
Just a good load in Lapua SRP 6.5 brass and 140 Bergers (loaded by Copper Creek no less)

You make my junk look good.......haha......

 

[kthomas]

Put me down as a non believer.

The longer I do this shit, the more I’m convinced most legacy reloading dogma is total nonsense.

I don’t even do load development anymore really. I just pick a speed and pick a seating depth out of the air, and as long as I drop powder to the kernel and make sure every round turns out the same as the next, all it does is get me the smallest groups I’ve ever shot and half-MOA out past 1000 yards every time.

I'm of the same opinion.

The more that I reload and test, the more that I realize most conventional reloading dogma is complete bullshit. Reloading is so full of myth and lore it's unbelievable.

Just look at how the "Satterlee method" caught fire for a couple of years and how frequently it was propagated by allegedly great shooters and reloaders.

Tuning is the same. It's based off of statistically extremely weak data sets, with people making conclusions that don't actually exist (and that would be clear with much higher data sets).

I've yet to see any tuning "tests" that has a compelling sample size of data that's worthy of drawing any real conclusions from. It's the same bullshit as the "Satterlee method" but in a different form. People want an "easy fix", which is what tuners and the "Satterlee method" (and others) promise. And because the vast majority of people do very little real testing themselves, they draw faulty conclusions from their own weak datasets.

The real true secret to reloading is to use good quality components, good quality reloading gear, and developing a consistent and repeatable reloading process.

 

[TheOfficeT-Rex]

Tuning is the same. It's based off of statistically extremely weak data sets, with people making conclusions that don't actually exist (and that would be clear with much higher data sets).

I agree with this, on at least some level. But I am interested in what you would consider a higher data set?

The more I think about it, the more often I come back to group size is the wrong metric. I don't think it gets any better or more informative by doing a 30 round group instead of a 5 round group. Tracking mean radius from point of aim across several groups may be a solution, but it's a bit fiddly/time consuming to do by hand as I don't have access to an electronic target, and, as highlighted, I'm as lazy as everyone else.

ETA: That "secret sauce" is pretty close to where I'm at these days - more time to think about and work on my fundamentals and positional shooting.

 

[AccuSol-ERN]

I'm of the same opinion.

The more that I reload and test, the more that I realize most conventional reloading dogma is complete bullshit. Reloading is so full of myth and lore it's unbelievable.

Just look at how the "Satterlee method" caught fire for a couple of years and how frequently it was propagated by allegedly great shooters and reloaders.

Tuning is the same. It's based off of statistically extremely weak data sets, with people making conclusions that don't actually exist (and that would be clear with much higher data sets).

I've yet to see any tuning "tests" that has a compelling sample size of data that's worthy of drawing any real conclusions from. It's the same bullshit as the "Satterlee method" but in a different form. People want an "easy fix", which is what tuners and the "Satterlee method" (and others) promise. And because the vast majority of people do very little real testing themselves, they draw faulty conclusions from their own weak datasets.

The real true secret to reloading is to use good quality components, good quality reloading gear, and developing a consistent and repeatable reloading process.

Indeed. Too much variability in components/methods to come to a concrete one-size-fits-all conclusion.

There probably is some merit for certain methods.......this would explain why FGMM 168bthp can be shot out of a 16" ar10 or 26" bolt gun and achieve great accuracy.......not to mention all of our pet load recipes for different cartridges that seem to shoot really good regardless of parts used and barrel lengths.......

I think this is part of the fun of this game.......always trying to build a better mouse trap......heaven forbid we figure it out one day.

Ern

 

[kthomas]

I agree with this, on at least some level. But I am interested in what you would consider a higher data set?

The more I think about it, the more often I come back to group size is the wrong metric. I don't think it gets any better or more informative by doing a 30 round group instead of a 5 round group. Tracking mean radius from point of aim across several groups may be a solution, but it's a bit fiddly/time consuming to do by hand as I don't have access to an electronic target, and, as highlighted, I'm as lazy as everyone else.

Well it's certainly not the standard few 2-3 round group "tests" that shooters and manufacturers advocate for.

I think a good starting point would be shooting a bunch of 5x5's, over a few days of various different conditions.

Each day of testing shoot a 5x5 with no tuner as a control group. Then shoot 5x5's of various tuner settings. Do it over multiple days, and see what bears out day after day. I bet the results would shock a lot of tuner advocates.

Of course no one is going to do it. Tuner manufacturers don't need to do it because they have nothing to really gain - they get a lot of people on their statistically meaningless "tests". Shooters won't do it because they are looking for a quick fix, and don't understand statistics. And money and time, blah blah blah.

It's easier to fool someone than to convince someone that they've been fooled...

 

[R_A_W]

It's the same bullshit as the "Satterlee method" but in a different form. People want an "easy fix", which is what tuners and the "Satterlee method" (and others) promise. And because the vast majority of people do very little real testing themselves, they draw faulty conclusions from their own weak datasets.

Edit: I was wrong, ignore my Satterlee comments

You’ve almost laid out one of the best arguments in favor of Scott Satterlee’s method… most shooters simply aren’t that consistent in their load developments. The Satterlee method a structured way for inexperienced people to find a load that works with minimal equipment and no assistance while minimizing guesswork.

 

[kthomas]

You’ve almost laid out one of the best arguments in favor of Scott Satterlee’s method… most shooters simply aren’t that consistent in their load developments. The Satterlee method a structured way for inexperienced people to find a load that works with minimal equipment and no assistance while minimizing guesswork.

Technically the Satterlee method doesn't find anything. Those velocity "nodes" are purely fictitious, but can certainly look real if you have only a sample size of (1) per charge weight in your Satterlee ladder.

If you have good (enough) reloading techniques and process, equipment and components, you will make good (enough) ammo.

The only real thing the Satterlee method is good for is for finding approximate velocities per charge weight, and where pressure occurs. But then that's not the Satterlee method, it's just a simple charge ladder.