WHY do velocity nodes exist?

[LGKLAS]

Hey Alex..... I'm gonna' break my tradition of continually asserting that "no two similar barrels, no two similar bullets, no two similar rifles tune and shoot the same" because as of right now I'm fairly convinced that RL17 and H4350 show such similar burn characteristics that you can tune up a rifle with one, switch powders and match velocity and be back in the node.


(WHEwwww, I don't think I've ever put that idea'r into words before.... I might just regret it! LOL)

BTW if'n y'all would lay that frickin' ladder down and LISSEN to guys like Borden you'se might see that them "silly flat spots" actually map as a sine wave.......

This "Long Range guys VS Short Range" guys is what's silly.



Think Bart....there's a man can TUNE.....

alinway- in my limited experience, I do not think you will regret it. Me (I'm part of the group size equation) and my rifle 'like' a MV of around 2700 fps. I use 4 bullets and 3 powders (RL-17 and H4350 are two, coincidentally) and I load for that velocity. And me/rifle/MV shoot the best groups at around that velocity (rough numbers +/- 40 fps). Does not make any difference to me if what's happening is I've caught the sine wave, or am in a node by any name, it just works. Using bullets weighing 140-142 and charges of 40.4-44gn's. Doesn't matter as long as I am in that MV range. But then I am not among those striving for a 0.25 MOA group and am not a competitive shooter. I am retired. Sub MOA works for me both as far as building loads that will do that and the MV gets me out to 1000yds (6.5mmCM) to hit steel (not hunting) and I am having fun. Per Strelok my come up at 2670 at 1000 is 8.5 mils and at 2710 it is 8.3 mils. 6.8". Works for me.

PS: I think you can put me in the previously mentioned 99.9% group. Not at all being snarky here or above because I attribute some of my success to my reads of the info in these forums and threads like these. Posts by competitors, and seekers of .25 MOA groups, etc.

 

[rkittine]

Engineering wise I am totally in agreement with the sine wave example, but didn't I read in one or more accuracy shooting books or articles, that you were not looking for the null part of the wave, but the beginning or the movement, I believe the upward movement, but I would think that most people would not have the equipment to tell, just resulting consistent speeds and groups.

Bob

 

[alinwa]

Engineering wise I am totally in agreement with the sine wave example, but didn't I read in one or more accuracy shooting books or articles, that you were not looking for the null part of the wave, but the beginning or the movement, I believe the upward movement, but I would think that most people would not have the equipment to tell, just resulting consistent speeds and groups.

Bob

OK..... ..... there's not enough paper for me to bring forth the entire theory of sine wave tuning but from my experience with the guys who came up with the rules I must disagree a liddle. I, for instance, use neither null nor rising, quite the opposite.

(BTW it was Bill Calfee who spake/wrote even wrote a book which brings forth the "stopped muzzle" philosophy which some call "null")

The accepted place to work occurs right over the leading crest of a sine wave, right where a surfer's head sets although some have found success using the bottom of the swing. IMO you're not looking for maximum velocity of movement but for maximum shot displacement from the bending of the barrel. (Yes, barrels bend, big time) But this is purely speculative, suffice it to say that just over the crest WORKS....

And you find this area by SHOOTING IT......... you graph the group centers by shooting your groups along a horizontal line and when your groups rise up to a crest and start to drop again, this is where you tune.

(This is kinda' the same as a plateau or a flat spot on some of the ladder workups and since most don't shoot all groups over a chrono these plateaus get mis-named "velocity nodes" sometimes)

And here's a key to the entire equation, this sine wave tuning IS DISTANCE SPECIFIC!!!!! You can only tune out the vertical at your intended yardage!!!!

Draw it on paper or go throw a football in the yard and this becomes apparent.

 

[Webster]

I have been reloading for 55 years, and I shoot a lot - I haven ever seen a "velocity node"

It's hard for me to believe that a velocity node means you increase the powder charge a little and no velocity change. Seems to defy the laws of physics.

 

[gunsandgunsmithing]

Im a chain rattler myself. Love you guys tho.
Speaking of high speed photos ive been trying to find a video i seen of a sporter model seven in 223. The barrel looked like it whipped a foot up and down. That was an eye opener. The nightforce scope on a steel picatinny base with those huge 6 screw rings looked like a wet noodle. Looked like the base moved an inch over the bridge area. I cant believe we hit nothin after seein that

Ever shot RF Br? Some of those guys will have a tuner that weighs a pound on a 26" .850 straight barrel. You can watch the barrel bounce! That said, there's a lot more going on than this "bounce", where tuning with amplitude and natural frequency is concerned. If only, it were that simple.

 

[Dusty Stevens]

Ever shot RF Br? Some of those guys will have a tuner that weighs a pound on a 26" .850 straight barrel. You can watch the barrel bounce! That said, there's a lot more going on than this "bounce", where tuning with amplitude and natural frequency is concerned. If only, it were that simple.

Yes i shoot it. With a 28” .850 barrel and one of your tuners with bloop tube. Like a diving board

 

[CharlieNC]

You need a 21.75 inch barrel.

 

[gunsandgunsmithing]

Yes i shoot it. With a 28” .850 barrel and one of your tuners with bloop tube. Like a diving board

I knew you were crazy!
RF is a different animal. Ammo, ammo, ammo...and everything like dat!

 

[Dusty Stevens]

I knew you were crazy!
RF is a different animal. Ammo, ammo, ammo...and everything like dat!

I dont get into those games. If i buy x act, midas or tenex and get a flyer it was probably me. Never bought more than a brick at a time and do just fine. Im like that guy with a chargemaster and no annealer that still wins every once in a while when the wind blows real good

 

[gunsandgunsmithing]

I dont get into those games. If i buy x act, midas or tenex and get a flyer it was probably me. Never bought more than a brick at a time and do just fine. Im like that guy with a chargemaster and no annealer that still wins every once in a while when the wind blows real good

Not wanting to sidetrack the thread but I've always been able to tune any rf ammo to its potential with small tuner adjustments. Still, all ammo is not created equal.

 

[Someoldguy]

It's hard for me to believe that a velocity node means you increase the powder charge a little and no velocity change. Seems to defy the laws of physics.

I'm not going to try and explain it, because I don't understand it well enough to do it in a few words. So I'll simply say I've seen it too, yes, it seems to defy logic, and the best generic explanation I am aware of is the Law of Diminishing Returns. Is it helpful? Not so far as I've been able to tell.

 

[gunsandgunsmithing]

If shooting compressed loads, you effectively slow the powder burn rate somewhat by essentially making one big powder kernel out of the entire powder column. Much of how mfg's change burn rates is by varying the shape and size of the kernels. More exposed area= faster burn, all else equal.

 

[Someoldguy]

If shooting compressed loads, you effectively slow the powder burn rate somewhat by essentially making one big powder kernel out of the entire powder column. Much of how mfg's change burn rates is by varying the shape and size of the kernels. More exposed area= faster burn, all else equal.

That's all well and good I reckon.

What is your theory when this happens and the load isn't compressed?

 

[gunsandgunsmithing]

That's all well and good I reckon.

What is your theory when this happens and the load isn't compressed?

I don't have a theory that explains that. I didn't mean to imply that compression is the sole reason for what you and others are seeing, either. I have no intention of debating anything. Just pointing out something that that I believe is a factor in it. I'm interested in what others have to say but just for my own knowledge.

 

[Someoldguy]

I don't have a theory that explains that. I didn't mean to imply that compression is the sole reason for what you and others are seeing, either. I have no intention of debating anything. Just pointing out something that that I believe is a factor in it. I'm interested in what others have to say but just for my own knowledge.

Fair enough. Just asking. Thanks.

 

[gunsandgunsmithing]

Fair enough. Just asking. Thanks.

Thanks and no problem. I know and have seen these powder plateaus myself. I would like to know HOW they happen because I tend to lean toward the side of physics. I agree with what was said earlier, that it seems to go against physics. There is likely an explanation that I don't see, yet.

 

[Dusty Stevens]

Maybe theres unburned excess powder coming out the muzzle after the plateau- cant get it all burned. I dont know.

 

[Homerange]

Im a chain rattler myself. Love you guys tho.
Speaking of high speed photos ive been trying to find a video i seen of a sporter model seven in 223. The barrel looked like it whipped a foot up and down. That was an eye opener. The nightforce scope on a steel picatinny base with those huge 6 screw rings looked like a wet noodle. Looked like the base moved an inch over the bridge area. I cant believe we hit nothin after seein that

Funny that the first varmint rifle I reach for is a Model 7 in 223 sporting a stainless can and a 16x scope and it out-shoots all other rifles I have. Each to their own I guess.

 

[Mikemci]

Maybe theres unburned excess powder coming out the muzzle after the plateau- cant get it all burned. I dont know.

Then why would the mv start rising again, after the flat spot, when powder charge is increased? If your reaching max powder burn, was the cause of the flat spot?

 

[Bc'z]

Then why would the mv start rising again, after the flat spot, when powder charge is increased? If your reaching max powder burn, was the cause of the flat spot?

I'm thinking the flat spot is your wiggle room +/- on your charge weight and barrel harmonics.If your powder is at 100% burn given barrel length, more powder isn't going to give you more velocity.
I'm also thinking " harmonization"any given cartridge, case capacity, barrel length, twist rate combination is only going to push said projectiles accurately to certian speeds.
After that things just come undone on paper and in the air.
Just my thoughts after 6 months of reading the more technical side of things.
B