Adjusting a Tuner using sound

Jim Pollard said:
Keith
The stethoscope head is attached to the stock, under the action area with tape. That way it would not have any influence on the barrel its self. I am not an engineer, just common sense ( shop teacher) but any thing attached to the barrel would result in false readings. Is that wrong?
Jim
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Jim,
The best idea might be to try placing the stethoscope on a fixture below the barrel without touching the barrel. The rearward motion of the barrel could confound the measurement, but with two sensors it might be possible to adjust for this. Getting something useful from sound is a bit of a long shot, but if it's cheap and fun, why not try it?

Keith

PS. You're right, weight on the barrel will change its motion, but if the weight were small, then the change would be small. Or, if you find the tune with the sensor in place, then when you take the sensor off, replace it with an equal amount of weight to keep the tune.
 
Kent Owens said:
Will Hickman did a lot of tests on this several years ago. He went by WillH on the forum. One thing I found interesting from his tests was that the vibration ws the virtually the same when you dropped the firing pin on a fired case. The lines on the graph were just accentuated, but the same pattern. You may do a search for posts by WillH. He was an electrical engineer, I believe, and had the means and necessary tools to do such testing.
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Just a thought but is it possible to ignite a rimfire cartridge with an electrical pusle thus doing away with the firing pin and attendant motion? Also, rimfire ammo is cheap and I have lots of time to dial in a tuner. However, this kind of stuff is interesting and who knows, it may lead to something universally useful.
 
If you would like a small donation for your research I would be glad to donate.

Semper fi
pickles
 
James Allen said:
Just a thought but is it possible to ignite a rimfire cartridge with an electrical pusle thus doing away with the firing pin and attendant motion?
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I doubt that a priming compound developed to ignite from brisk compression would be likely to exhibit the same ignition characteristics when ignited by other means. Were that the case, then cartridge performance could be expected to be different & the readings would be irrelevant to a tuning process.
 
Question: If we are using a microphone to pick up sound, feeding that to a microphone, and then loading into a PC to see the wave forms isn't the time that it takes for us to even detect the sound (or vibration) AT THE PC directly related to the speed of sound? Meaning that it takes some amount of time for the vibration to be "heard" by the stethoscope, that vibration then passes through "air" at the speed of sound, before it is "heard" by the microphone and translated into electrical signals ..... at which point it moves lots faster ..... or not?

Added after here: If this is true, then the vibrations, or waveforms potentially are valid, but the time relationship between the actual vibration and the "recording of that vibration" needs to be adjusted by some factor of time which is based on the speed of sound. Maybe as simple as using the length of the stethoscopes rubber tubes +/- the true distance to the microphone pickup ......

If the whole delay thing because of speed of sound theory is even valid.
 
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Fred
I am not sure where you are going, but there is a time lag between when the trigger is pulled and the wave can be seen. I can see a small time lag from when the noise of the shot is heard on the graft and the sound wave appears on the computer. I still feel that the graft of waves mean something. I have not taken the one gun I think is very close to the range to test shoot. The deeper I get into this the more complicated it gets. For example, the amout of weight added to the tuner makes a differance in wave shapes. Second, I have looked at about 75 to 100 test shots, from 3 differant guns. A wood stock's waves are differant from a fiberglass stock. The total length of the sound is about 1/2 a second, with the bullet exiting the gun in around 0.003 of a second, most of the wave is reaction to the shot, not the time in the barrel. The answer to a number of questions I don't know far excedes things I feel I can hang my hat on and feel like are true. before the computer is attached. So much more testing is needed and this takes time. The weather has finally started to warm up so I can now do some test shooting.
I have done a lot of taping the barrel with a stephoscope and doing futher tests when the node sounds to be under the tuner and not on the barrel. I then test shoot with the stephoscope attached to futher elemite test areas. I hope to get repeatable waves from differant guns, but I am not close at this time.
Later
Jim
 
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Hey Jim,

I think the work that you are doing is great. I made myself crazy with all of this a few years ago (but I tend to do that) .... but you guys have gotten allot farther than I did. The only thought that I had was this ... there was a discussion that most of the vibrations seemed to be coming after the bullet "theoretically had left the barrel. What my thought was it that there is a delay in the actual vibration and the point when it is recorded due to the sound having to travel through air at the speed of sound and that the vibrations may in fact be happening while the bullet is still in the barrel.

I think that was what was being discussed .... if I missed it, sorry for jumping in ....
 
Fred
Jump in all you want. It gets lonely walking out here. I feel sure the bullet has cleared the barrel before the computer has compleated making the sound record. I also have a time measurment on the graph and the total sound lasts about .024 seconds and the bullet cleard the gun in about 0.003 of a second others tell me. I can see a change in wave pattern at 0.003 on the graph. The time can measure down to 0.001 of a second.
I have one gun ready to test shoot at the range and think I am within 10 clicks of a good tune for eather 25 yards and 50 yards. I don't think the same tuner setting will work for both distances. I think there may be a 5 click differance between the to distances. It is target testing time.
Jim
I spent today working on a second BR gun and think I have it down to a 10 click test area. I added 7 and 1/2 ounces to the gun tuner. The wave pattern got much better.
 
If you're OK with sharing what you used and how you set things up I might be into trying a little on my end too. Guess it depends on cost ..... let me know

Fred
 
I dunno man....each string on a guitar sounds different but they're all in tune. Further, any string can be detuned and the other 5 be tuned to a point that makes the detuned string back in tune. However, last time out I couldn't hit nothin' with my guitar - last place.
 
New here but...

you guys are doing jut the kind of test that I was considering performing myself.
I am a musician and sound engineer as well as a prone shooter so I know a bit about what you're doing.

In MY experiment, I was planning on using an electromagnetic sensor (guitar pickup) to record the motions of the muzzle as the shot is fired and have a second microphone in very close proximity to the muzzle to capture the blast from the gasses behind the bullet - which will give you a pretty exact timing for the bullet exit.
Record both into my laptop through my audio interface - pickup on track 1, microphone on track 2 - and at the maximum possible sample rate (96k) which should give around 300 data points during the "barrel time". Then you can directly see the muzzle motion AND the point of exit on the same timeline.

If I remember my electromagnetics theory, the resulting waveform from the pickup would be a representation of the velocity of the muzzle, not the position. So we'd be looking for a point where the wave crosses zero (or thereabouts) for optimum tune - or am I completely wrong about that...?

Anyhow, now our winter season is over I might just have to give it a go myself.

Regards,
K.
 
Can sound waves influence a projectile's path? Like a rimfire bullet just leaves the barrel -is it possible for the sound waves to influence the bullets path AFTER IT HAS LEFT THE BARREL -even if it is just a very minute influence?
 
Al and MKnarr

Varmint Al said:
esten-rv-no-tuner-50yd.png

I am not sure what is actually being measured, but... Looking at the first 0.003 seconds of the curve looks very similar to the FEA calculations of the muzzle projection curve for Esten's 22LR rifle with the reverse taper and no tuner. The timing is remarkably similar.
Good Hunting... from Varmint Al
coyotel.gif
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Al and MKnarr,
I have been doing some research along the same line as you and am working on two new articles. I have a question, one set of graphs with the two different weights verses the one Al put up by a quote. Where did the chronograph information come from? What make of chronograph was used and was a buffer placed in front of the chronograph? I am guessing that the two velocities were taken one after the other without running a string of ten shots gathering the information about SD, ES, or average velocity.
My article will discuss tuning, but this is not my interest in the article. I am very curious about the chronograph information and we maybe able to help each other.
Sorry about being away from the forum so long, I did a little catch up reading today.
Bob Collins
 
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