VELOCITY NODE

[CharlieNC]

To improve on the ten shot velocity ladder node, this was one shot each with finer increments for 21 shots. You can see nice nodes at 38.0-38.5, 39.2-39.8, and looks interesting at 40.2-40.8! These are spaced around one grain apart, reflecting the harmonic behavior.

Well this is calculated data where the velocity is a perfect linear increase with charge plus adding a random number from the normal distribution with SD=6 to each result. Do this several times with any desired SD and charge weight increment, and you can eventually "see" anything you are looking for.

Say anything often enough and it will become a fact!

 

[darkangel_r2]

I always say the result of any test is valid only if its results are repeatable. If you want to assign a velocity and point of impact to a charge level you are going to need more than one shot. Any method that assigns a bulk stat (average velocity, sd, group center, ect) to the outcome of a single shot is building a house on quicksand.

 

[CharlieNC]

I always say the result of any test is valid only if its results are repeatable. If you want to assign a velocity and point of impact to a charge level you are going to need more than one shot. Any method that assigns a bulk stat (average velocity, sd, group center, ect) to the outcome of a single shot is building a house on quicksand.

Yes, convoluted logic! Surprisingly a single shot ladder on a target is much more repeatable than the Chrono. And you really have to try to screw up a two shot ladder.

 

[acloco]

First time I read the title of this thread, the O in NODE looked like a U. Damn trifocal lines!

Thought there was something new that I needed to know.

 

[Olde Man]

Does your point of impact on the target follow the velocity increase or can you see the effects of positive compensation?

 

[CharlieNC]

Does your point of impact on the target follow the velocity increase or can you see the effects of positive compensation?

Both, poi is the sum of those factors.

 

[JEFFPPC]

I am confused. How have I shot so well for so many years with out Positive Compensation, knowing my linear increase date, or using a chronograph. I guess it pays to be a lucky sap. I think I will just keep muddling along shooting small. You guys have fun.

 

[Olde Man]

Many times my higher velocity loads moved the impact position down on the target. I try to pick my node by using either the high impact position or the low one when barrel movement is at the minimum. My observation would be that the velocity at 100yds is not the major player. I have been looking at this for a while and haven't been able to sort out all of the variables such as changes in mirage etc as it takes a while to shoot this without having to have to consider barrel and ambient temp changes.

 

[Olde Man]

No offence meant JEFFPPC I am just trying to wrap my head around what appears to be more than a casual observation.

 

[jelenko]

I think the question is whether the velocities of a string of one shot each at a different powder charge is enough data to make any conclusion.

 

[CharlieNC]

Velocity uniformity and positive compensation are useful, complementary tools. But a single shot "Saterlee" Chrono ladder is not the route to meaningful information.

 

[PigButtons]

Velocity uniformity and positive compensation are useful, complementary tools. But a single shot "Saterlee" Chrono ladder is not the route to meaningful information.

SARCASM alert!
I disagree @CharlieNC, I think it's meaningful, just not useful.

 

[CharlieNC]

SARCASM alert!
I disagree @CharlieNC, I think it's meaningful, just not useful.

In this situation my vocabulary is not sufficient to distinguish the difference between meaningful and useful LOL!

 

[JFrank]

Velocity uniformity and positive compensation are useful, complementary tools. But a single shot "Saterlee" Chrono ladder is not the route to meaningful information.

This is confusing, your advacting one shot ladders in your first post and now saying it’s not meaningful ?

 

[CharlieNC]

This is confusing, your advacting one shot ladders in your first post and now saying it’s not meaningful ?

It was a satire, maybe not clear. The graph is from calculated data which is a perfect straight line correlation between between charge weight and velocity plus add a random number from the normal distribution with SD=6. Meaning there is absolutely no node, except what appears to be so from typical noise.

 

[darkangel_r2]

Velocity uniformity and positive compensation are useful, complementary tools. But a single shot "Saterlee" Chrono ladder is not the route to meaningful information.

Especially if they shoot that with a magneto that is hanging off their barrel. I've seen so many single shot velocity ladders with a magneto chrono on youtube that it makes me want to weep for all the components wasted.

 

[JFrank]

It was a satire, maybe not clear. The graph is from calculated data which is a perfect straight line correlation between between charge weight and velocity plus add a random number from the normal distribution with SD=6. Meaning there is absolutely no node, except what appears to be so from typical noise.

WHAT KIND OF A SICK SOB ARE YOU!!!

just kidding

 

[CharlieNC]

WHAT KIND OF A SICK SOB ARE YOU!!!

just kidding

I worked in R&D for many years, and being a wise a** was a necessary trait at many times.

 

[miningshawn]

I would like to thank the OP! Way to go CharlieNC.

I have been doing this for years. The first shots in my load development are velocity ladders, but I typically use a 0.2 or 0.3 grain increment. My observations (your observations probably differ from mine, and that's fine) have been that flat velocity regions are more stable and predictable, and tend to have good ES/SD. The area on the graph from 39.2 to 39.6 would make me very happy!

I move to OCW groups after a velocity ladder, and then final groups with seating depth/barrel tuner.

Using this method I don't waste as many components on a new work-up. I can focus on the flat areas with 5 shot groups.

Putting my money where my mouth is, here is a snapshot of the very first loads in a completely new caliber.



I am going to run these across a Magnetospeed in three series. I am going to average all three series. Once I plot the velocity graphs, I am going to focus on the flat spots in the velocity node and find the optimal charge weight in 0.1 grain increments. Once I have determined an optimal charge weight I will finish with tuning on one rifle (because I have a Cortina tuner/muzzle brake on it that works great for me) and seating depth testing on the other (because BR folks are kind of down on muzzle brakes).

"Let the target tell you"
"My way is better"
"This doesn't work"
"My super expert friend says"
"Chronographs don't work"

I've heard it all. I am a believer in velocity nodes. I am a believer in barrel harmonics. I have never pulled a full string from min-to-max like CharlieNC before and it is great that he took the time and components to do this.

Thanks again, CharlieNC

BTW: I have also observed that flat spots in the velocity greatly tend to be the lowest groups when point of impact is unchanged.

 

[Coyotefurharvester]

Say anything enough times and it becomes factual, .4 gr node is narrow for my cheap scales. I need a wide node with minimal vertical. Or I C H S.