WHY do velocity nodes exist?

[Dusty Stevens]

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.

Looks like you took my post the wrong way. I have one myself but it only has a 6x leupold

 

[gunsandgunsmithing]

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

Is 100% burn even possible?

 

[Bc'z]

Is 100% burn even possible?

Given some of the barrel cut down tests I've seen I would say yes.
But I couldn't tell ya for certain, given your expertise and experience you could probably answer that better n me.
I'm a student of reloading and here to learn.
With all the info I've taken in and my limited experience I was posting my thoughts n observations on the subject.
Example, my 06'. I wanted 2900 fps didnt get there got to upper 2800's given 24" barrel, case capacity, powder selection & bullet.
Could I get there accurately with more barrel? Probably. But at what point do I lose velocity and or grouping? Where is the sweet spot?
So you see the overwhelming amount of information has my head swimming with thoughts and questions

 

[alinwa]

OK..... it looks AGAIN like I disagree with ever'body in the thread

What I'm trying to say is, for me, the "flat spots" AIN'T VELOCITY RELATED..... I shoot thousands of rounds over chrono, weighing every charge to the powder kernel and I don't relate to velocity flat spots with the exception of "just as you top out a specific powder, it may plateau velocity-wise".... just as it starts destroying cases.

But FOR ME..... add a few kernels, get a little velocity is how it works. EVEN THOUGH my groups may be (expect to be) hitting a "flat spot" or even going DOWN as velocity goes UP.

For ME, once I got real careful with graphing my results I found out "what you see" or "what you think" or "what you remember" doesn't always jive with "what you measure."

I measure velocity,

A lot.

And I measure (weigh) my powder charges,

A lot.

And if others here are finding velocity plateaus with WEIGHED powder charges over the same chrono on the same day (same light conditions etc) then I'm sorry to say I just haven't experienced this.

"Here I Go Again, On My Own...."

LOL

 

[Bc'z]

OK..... it looks AGAIN like I disagree with ever'body in the thread

What I'm trying to say is, for me, the "flat spots" AIN'T VELOCITY RELATED..... I shoot thousands of rounds over chrono, weighing every charge to the powder kernel and I don't relate to velocity flat spots with the exception of "just as you top out a specific powder, it may plateau velocity-wise".... just as it starts destroying cases.

But FOR ME..... add a few kernels, get a little velocity is how it works. EVEN THOUGH my groups may be (expect to be) hitting a "flat spot" or even going DOWN as velocity goes UP.

For ME, once I got real careful with graphing my results I found out "what you see" or "what you think" or "what you remember" doesn't always jive with "what you measure."

I measure velocity,

A lot.

And I measure (weigh) my powder charges,

A lot.

And if others here are finding velocity plateaus with WEIGHED powder charges over the same chrono on the same day (same light conditions etc) then I'm sorry to say I just haven't experienced this.

"Here I Go Again, On My Own...."

LOL

You won't be on your own for long.

 

[Darrel Martin]

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.

I think it may relate to the fact that there are different harmonic phenomena occurring. The barrel whips up and down ,probably in an oval or figure of 8 pattern.This results in the sine wave move ment of the point of impact.
The barrel also has waves of expansion and contraction moving up and down the barrel at the speed of sound in steel resulting from the 50-60,000 psi explosion in the chamber.Given that the bullet starts from a speed of 0 fps, and the speed of sound in stainless steel is about 5000 m/s, these waves move back and forth through a well bedded barrel multiple times before the bullet exits.
This not only can affect the dispersion of the bullets (as there will be more dispersion if the bullet exits at a time when there is greater expansion of the muzzle end of the barrel)but it could also affect pressure and therefore velocity based on whether the bullet encounters a wave of expansion or contraction and whether this wave is traveling in the same or opposite direction as the bullet.
A small change in a charge could produce a counter intuitive failure to increase or decrease the velocity if the difference in the charge caused the bullet to encounter a different wave pattern .

 

[270WinDude]

All I know is it gets confusing when I compare theories to my airgun. Spring piston, and when I first got it I was shooting .2 and below at 15 yards and under with some pretty extreme velocity spreads yet it was my most accurate airgun, even out to 50 yards and 1 has a SD of about 7fps. For centerfire I'm leaning towards the harmonics and timing of bullet release... Not saying that all charges are created equal though. It's interesting that XX.A grains gives a spread of 12 where XX.B gives a spread of 8...

 

[dcali]

OK..... it looks AGAIN like I disagree with ever'body in the thread

What I'm trying to say is, for me, the "flat spots" AIN'T VELOCITY RELATED..... I shoot thousands of rounds over chrono, weighing every charge to the powder kernel and I don't relate to velocity flat spots with the exception of "just as you top out a specific powder, it may plateau velocity-wise".... just as it starts destroying cases.

But FOR ME..... add a few kernels, get a little velocity is how it works. EVEN THOUGH my groups may be (expect to be) hitting a "flat spot" or even going DOWN as velocity goes UP.

For ME, once I got real careful with graphing my results I found out "what you see" or "what you think" or "what you remember" doesn't always jive with "what you measure."

I measure velocity,

A lot.

And I measure (weigh) my powder charges,

A lot.

And if others here are finding velocity plateaus with WEIGHED powder charges over the same chrono on the same day (same light conditions etc) then I'm sorry to say I just haven't experienced this.

"Here I Go Again, On My Own...."

LOL

Just wanted to point out that I was cool before it was cool to be cool. (See post #24).

 

[gunsandgunsmithing]

Just wanted to point out that I was cool before it was cool to be cool. (See post #24).

But that's always been cool.

 

[alinwa]

Just wanted to point out that I was cool before it was cool to be cool. (See post #24).

Sorry man...... I'm just checking in between building a 65lb rest for my Heavy gun down in the shop and I sometimes ferget where I am and just get all cornfuzzled... I KNOW that you and Mike for instance spend time with and thoroughly understand tuning, and there are probably others even in this thread but I just FORGET who's been in this one

I got a liddle carried away with my hyperbowl there....."everybody" wasn't necessary

 

[dcali]

But that's always been cool.

Now I'm just confused! Am I counter-culture cool, or just another hipster? Ah well. Either way, I can't see flat spots, which might just mean I need bifocals.

 

[Ned Ludd]

A lack of evidence for something is NOT proof that it doesn't exist. Way too many people that know very well what they're doing at the reloading bench have observed this phenomena. If you have never encountered flat spots in your charge weight vs velocity curves, try using some different primers. Sometimes that is all it takes.

 

[dcali]

Yes, just to be clear, I've never seen it on my rifles. I won't go as far as saying it can't happen. Perhaps it's powder/primer related, although I can't imagine how. Maybe some sort of coating or a difference in solid vs gas ejecta from the primer? I'm not really knowledgeable about either.

 

[G7BC]

In the ladder test below. What ever you want to call that top 4 shot (thingy) with over 100 FPS and 2 gr of powder spread? It was good for 3 IBS 1000 yd records that following year. What ever it is called? let me know.

What distance was this shot at?

 

[David Milisock]

What distance was this shot at?

Natural resonance. Tesla wrote about it over 100 years ago.

 

[mikegaiz]

What distance was this shot at?

300 yds.

 

[jelenko]

once I got real careful with graphing my results I found out "what you see" or "what you think" or "what you remember" doesn't always jive with "what you measure."

++.

To level set, I do very little measuring velocity.

Even with that, I've seen enough of other's velocity to notice that, for a given charge of powder, the MV varies over, say, a 10 shot string. So, it seems natural that if the group size at a given charge is small enough, the average of that group could fall off the straight line of velocity vs powder charge. Because it seems 3 shot groups are commonly used by some in load development, it could be the small group size that is introducing 'artifacts' in the data.

 

[Ledd Slinger]

I don’t look at ES or SD. I watch them when I’m shooting but I don’t really care what they are for the most part. I only start to care about velocities when they start to show me that a powder is no longer giving me a complete burn down the bore (crazy velocity spreads or no gain in speed) or I am reaching max pressure. I am more concerned with group sizes and Point of Impact (POI) on the target over a spread or SD of velocities.
Just yesterday I was shooting some 3 shot groups with various loads thru one of my hunting rifles at 635 yards. One of the loads produced identical speeds on all 3 shots of 3197 fps with a 220gr Berger bullet. But on paper, it was one of the worst groups as all 3 shots were perfectly strung vertically on top of each other in about a 7” group. Speeds looked great, but when I looked thru my spotter I noticed right away that the group wasn’t worth a damn on paper and that the identical speeds don’t guarantee anything.