Which barrel profile would act stiffer?

[darkangel_r2]

With all due courtesy, your analysis and spreadsheet isn't going to give anyone any information worth looking at either. You have received a lot of good advice and suggestions from the forum. The fact that you are not willing to consider that expert advice does not make your calculations any more relevant by putting them in excel.

It will tell you which barrel profile should act stiffer. I literally made this thread because I wanted this information.

Everyone told me they act the same, and that's more or less true. I wanted more information to base a decision on. If Lilja barrels felt that doing this analysis is worthwhile enough to put a whole page together for it maybe you should consider what I am doing with more enthusiasm than skepticism. Unless this information that someone is handing you on a silver platter is somehow a burden on you.

And excel is nice as it cleans up my rounding errors. Turns out the LV is 0.15-0.5% stiffer than the LP. I don't think that is worth the extra weight as it is near 7% heavier. The Palma is 3.5% stiffer than the LV and weighs the same but will feel less handy as it has a higher MOI.

This information is useful when picking from barrels with the same length and similar weight. Most people won't care. But now we have it for the people that do.

NOTE: ADDED DIFFERENT LENGTH STIFFNESS COMPARISON FUNCTION.

I think if I do a ratio of deflection between the two barrels the only items left are length and moi. A ratio drops a bunch of terms should be able to use my initial calculation to tell which is stiffer with any length as long as the material is the same.

Thanks again for the input guys.

 

[KMart]

I think we have a new fguffey!!!! SON OF GUFFY!!!!

Needs to be right and can prove it. He is the only one that knows how.

 

[Tommie]

Silly question

Congrats to all who’d been troll-baited.

 

[darkangel_r2]

I checked my model against lijas (ratio of barrel stiffnesses for .925" muzzle with a 5" cylinder and a .75" muzzle with 5" cyl and my ratio was 0.88% off of lijas. So I don't think there is anything significantly wrong with my math or assumptions made to produce the model. Probably a discrepancy between me and lilja regarding bore and thread definitions.

 

[JFrank]

Have you gave consideration to running all these past Carson Lilja ?
He is a member of this forum.

 

[darkangel_r2]

Have you gave consideration to running all these past Carson Lilja ?
He is a member of this forum.

I did not know that. I'll send him a PM.

 

[CharlieNC]

If accuracy was only as simple as stiffness!

 

[SEGARE]

I checked my model against lijas (ratio of barrel stiffnesses for .925" muzzle with a 5" cylinder and a .75" muzzle with 5" cyl and my ratio was 0.88% off of lijas. So I don't think there is anything significantly wrong with my math or assumptions made to produce the model. Probably a discrepancy between me and lija regarding bore and thread definitions.

Dood, you're right- we concede and are blessed to be in your presence.

 

[darkangel_r2]

If accuracy was only as simple as stiffness!

I like my barrels like I like my communists.

Room temp and stiff.

 

[darkangel_r2]

Dood, you're right- we concede and are blessed to be in your presence.

I'm just glad it seems to work. Hope some other people find it useful.

 

[Alex Wheeler]

Well its not a cracked flex plate. Well at least not alone, retaining bolts are tight. Small metal bits floating in oil pan. Rod knock or piston slap is likely. Assuming rod knock as the sound was louder on the underside of the motor right near the torque converter. Going to get a junk yard motor and rebuild it over the winter. I'll replace the rod bearings in the mean time to see if that quiets her down in the interim.

And BTW after building the methodology for the first barrel the process of calculating a "relative" moment of inertia for any barrel is really fast. Like 2-3 minutes fast.

Kill the cylinders one at a time and when the knock goes away you know which one it is. If it wont go away, it could be a main. Cracked flex plates sound a lot more like a tick, but more "tinny" sounding.

 

[CharlieNC]

I like my barrels like I like my communists.

Room temp and stiff.

Why? Does stiffest mean most accurate? Or just right stiffness? The barrel vibration modes, frequencies, and amplitudes which contribute to optimum accuracy cannot be summed up as simply as stiffness.

 

[darkangel_r2]

Why? Does stiffest mean most accurate? Or just right stiffness? The barrel vibration modes, frequencies, and amplitudes which contribute to optimum accuracy cannot be summed up as simply as stiffness.

Is there a way to calculate optimum profile for a certain chambering and length?

 

[CharlieNC]

Is there a way to calculate optimum profile for a certain chambering and length?

No, maybe? Varmint Al, Kolbe, and Vaughn report calculated frequencies and amplitudes and some actual measured results. These approaches tie in with positive compensation. Alternately Chris Long suggests a transverse vibration disturbs the uniformity of the muzzle opening and provides an Optimum Barrel Time table to use in conjunction with Quick Load to avoid this disturbance for optimum accuracy based on barrel length. None of these are sufficiently comprehensive to provide a thorough linkage of engineering/theory with rifle and barrel design vs actual testing. More on this later.......

 

[darkangel_r2]

No, maybe? Varmint Al, Kolbe, and Vaughn report calculated frequencies and amplitudes and some actual measured results.

Do you have a link to the Vaughn PDF? That's the only one I haven't gone through. The others are on my favorites tab.

And as to why I like more stiffness, stiffer barrels will dampen all vibration modes. And sufficiently stiff barrels will dampen the higher order modes into irrelevancy as their amplitude will be so small.

 

[CharlieNC]

Do you have a link to the Vaughn PDF? That's the only one I haven't gone through. The others are on my favorites tab.

And as to why I like more stiffness, stiffer barrels will dampen all vibration modes. And sufficiently stiff barrels will dampen the higher order modes into irrelevancy as their amplitude will be so small.

Try copy and pasting this link:

Rifle Accuracy Facts Full V 1.0 ( First Full Scan) : Harold R. Vaughn : Free Download, Borrow, and Streaming : Internet Archive

The author, who spent his career studying trajectories of nuclear missles and artillery shells, wrote this work after becoming dissatisfied with the accuracy...

archive.org

If you study these resources you will find the calculated frequencies with the large amplitudes are quite slow, while the reported results based on measurements and TARGETS are fast in the 5-20 kHz range. So there is a major disconnect between the two; I have studied this quite a bit and think I understand why and will be reporting on this soon.

 

[darkangel_r2]

Try copy and pasting this link:

Rifle Accuracy Facts Full V 1.0 ( First Full Scan) : Harold R. Vaughn : Free Download, Borrow, and Streaming : Internet Archive

The author, who spent his career studying trajectories of nuclear missles and artillery shells, wrote this work after becoming dissatisfied with the accuracy...

archive.org

If you study these resources you will find the calculated frequencies with the large amplitudes are quite slow, while the reported results based on measurements and TARGETS are fast in the 5-20 kHz range. So there is a major disconnect between the two; I have studied this quite a bit and think I understand why and will be reporting on this soon.

Thanks for the link I'll read through it over the weekend.

It is odd, I did a rough calculation based on the few graphs present in the 6ppc example they have. The lowest observable mode present on the graph had a frequency in the area of 2500Hz. The second(higher order) observable on the graph is 19000Hz.

Their example barrel was 22" a traveling soundwave in that barrel would have a frequency of around 5000Hz.

 

[Kracken McGraw]

 

[darkangel_r2]

Try copy and pasting this link:

Rifle Accuracy Facts Full V 1.0 ( First Full Scan) : Harold R. Vaughn : Free Download, Borrow, and Streaming : Internet Archive

The author, who spent his career studying trajectories of nuclear missles and artillery shells, wrote this work after becoming dissatisfied with the accuracy...

archive.org

If you study these resources you will find the calculated frequencies with the large amplitudes are quite slow, while the reported results based on measurements and TARGETS are fast in the 5-20 kHz range. So there is a major disconnect between the two; I have studied this quite a bit and think I understand why and will be reporting on this soon.

So my understanding in chapter 4 is he balanced his reciever and made it so all his bolt lugs had contact then added a recoil absorption system between the stock and the recoil lug that delayed the return impulse of the stock on the barrel until after the bullet left the barrel.

Is that correct?

 

[CharlieNC]

So my understanding in chapter 4 is he balanced his reciever and made it so all his bolt lugs had contact then added a recoil absorption system between the stock and the recoil lug that delayed the return impulse of the stock on the barrel until after the bullet left the barrel.

Is that correct?

That was one modification to address a single impulse, not vibraion. Most interesting is the frequencies associated with load development are high, I recall one around 10 khz. Kolbe also reports high frequencies. I observe 5-20 khz on my rifles during load development.