Studies graphing frequencies in barrels?

[ShootMo]

I just watched an interview with John Krieger. Of course barrel harmonics came up. Something he said gave me pause and my brain took off (lol). Does anyone here know of any studies where barrel frequencies were graphed as a bullet was fired?

I wonder if there's knowledge being left on the table? If one could include recorded frequencies into the rifle/load combination equation, could there be such a thing as determining sweet spots for accuracy BASED ON the barrel's harmonics? I know we "get there" with each individual barrel via load development. However, could a frequency map of sorts potentially provide a specific target to develop the load to?

Brain food. Lol

 

[Hugnot]

Priobably would be a huge variation of frequencies as there are a huge variation of factors like barrel thickness & length. Some barrels shoot various loads at near points of impact & the harmonics, like sine waves might look sort of like same. Interesting considering $60 plus for 100 bullets, $60 per lb powder with hazmat & shipping & scarce primers.

 

[Mikecr]

There are so many vibrations going on that I doubt the significant could be predicted.
It would have to be measured to know.

There is the Optimum Barrel Time (OBT) notion about one vibration(from case contact with chamber) traveling back & forth at the speed of sound in steel. The object being to avoid bullet release while a vibration is at the muzzle (opening the bore). It's Chris Long theory.
There are interference waves reflecting from the barrel/action, action/bedding connections, striking and engraving. These are described in Harold Vaughn's 'Accuracy Facts' book.
There is a barrel droop potentially taken out with pressure, causing muzzle whip. And the entire gun vibrating and recoiling. Varmint Al model examples.

I imagine they all add up to system & barrel nodes, which are separate and different from powder nodes (like an OCW).
IMO, working through this to cutting edge accuracy will always take testing.

 

[Jeff Heeg osoh]

This would be about at close someone could get to graphing a barrel in order to see pressure spikes in relation to harmonics. Pressure Trace II

Also charting impacts with powder charge increases and looking a point where a higher velocity impacts slightly lower then the previous round with less powder and a slower speed.

 

[MW204]

This would be about at close someone could get to graphing a barrel in order to see pressure spikes in relation to harmonics. Pressure Trace II

Also charting impacts with powder charge increases and looking a point where a higher velocity impacts slightly lower then the previous round with less powder and a slower speed.


View attachment 364308View attachment 364309

I hate to look/sound stupid but here I go anyway.
What are the top numbers on this graph, I'll step into it even deeper, what are the bottom numbers, velocity I'm guessing?

 

[Hawkeye Pierce]

TacomHQ structured barrels.
Yes I know it's a manufacturing company trying to sell things but it's very interesting.

Structured Barrels

tacomhq.com

They seem to have done some research on frequency.

 

[ShootMo]

TacomHQ structured barrels.
Yes I know it's a manufacturing company trying to sell things but it's very interesting.

Structured Barrels

tacomhq.com

They seem to have done some research on frequency.

This is exactly what I was wondering about. I couldn't imagine that "no one" would be doing this sort of work. Their method of harmonic manipulation is tooling and time intensive, but their science seems solid from what I can tell.

 

[Greyfox]

I have often wondered if one day there would some day be a "Magneto-speed type" device available that could measure harmonics….I recently received an EC(Eric Cortina) tuner/muzzle break as a Christmas gift from a buddy. Gave it a quick test at the range the other day on one of my PRS rifles, 6.5x47 with a Med Palma barrel. Need to do some more testing, but initial results were intriguing. Shot at 100/200 yards with the break set at 0, 3, and 6. The "0" setting was near identical to the results using my original Area 419 break.

 

[Beluebow]

Barrel Harmonics Mode Shape Movies

 

[RockyMtnMT]

TacomHQ structured barrels.
Yes I know it's a manufacturing company trying to sell things but it's very interesting.

Structured Barrels

tacomhq.com

They seem to have done some research on frequency.

This looks cool. Is it basically fluting with drilled holes?

 

[Hugnot]

This would be about at close someone could get to graphing a barrel in order to see pressure spikes in relation to harmonics. Pressure Trace II

Also charting impacts with powder charge increases and looking a point where a higher velocity impacts slightly lower then the previous round with less powder and a slower speed.


View attachment 364308View attachment 364309

Looks like 14 bullet holes with velocities, more powder? (lower) increasing left to right & some value, time? (upper) increasing left to right. Pattern described by bullet holes appears to be an undulating wave flattening out to right side. Low shots appear to periodically occur then flatten out at right side of target. Might this mean, like what most of us see, that accuracy increases along with velocity up to some point.

 

[ShootMo]

Click to expand...

This looks cool. Is it basically fluting with drilled holes?



Like Quote Reply

From what I read, their process is about canceling frequencies by drilling the recesses on opposing sides.

 

[Jeff Heeg osoh]

I hate to look/sound stupid but here I go anyway.
What are the top numbers on this graph, I'll step into it even deeper, what are the bottom numbers, velocity I'm guessing?

If you're asking about the chart with the orange aiming dots, the number above the impact is the powder charge and below the speed off a lab radar, this particular test was done on a rifle that only had 15 rounds down a new barrel prior to checking harmonics. - you would still see the typical heartbeat in harmonic on a seasoned barrel it would just be a little less sporadic. You just need a good day - overcast and calm to do this at 100 yards and you will find a sweet spot that the barrel likes. The key is to pick the node where the next faster charge impacts slightly lower then the previous as well as the horizontal being in the same zone.

The machine with the laptop and gadgets { Pressure Trace II } looks intresting I never got that but it does a good job with registering pressure and seeing secondary spikes on various loads.

JH

 

[Mikecr]

Be careful to understand that powder nodes are in no way connected to barrel nodes.
So testing that includes both, tells you specifically about neither. Just keep it in mind